Quite simply spellbinding. My favourite episode of Doctor Who since it returned to our screens and screaming pure quality from every second of its precious celluloid.

Adaptations are strange beasts. It all depends on your opinion of the original as to how you receive the altered version. With Dalek, BBC TVs adaptation of Big Finish's Jubilee, I felt Rob Shearman had missed a trick. He captured the drama and stunning dialogue of the original play but forgot one of the things that made the story so distinct, its sadistic and very funny black humour. Human Nature, in my opinion is an overrated New Adventure. Its good and it has a brilliant central idea but ive never been that fond of Paul Cornell's over-egged prose. Fortunately, Cornell has the incredible luck of wiping away the (frustrating) seventh Doctor and using the far more likable tenth, the added strength of Martha Jones and gets to turn the whole story into a hunt, which adds far more tension to the proceedings. All the important features are there?the romance with Joan, the fact that he embraces humanity; the incredible atmosphere of the Boy's school and the result is a TV adaptation that is vastly superior to its novelisation. An extremely rare feat.

Performances in the new series of Doctor Who are generally very good but occasionally a cast is assembled that is outstanding. The Impossible Planet/The Satan Pit is a good example and Human Nature is another. The three central performances sell the story so convincingly you are dragged against your will into their lives and feel a real connection with them. David Tennant outdoes himself in the central role of Dr Smith. It is enviable to any actor to be able to, in the middle of a series, play a completely different character. Usually science-fiction deals the alternative universe card to achieve this and the regulars ham it up but Human Nature depends on this being our Doctor and our Martha. Its frightening watching Tennant play John Smith, almost as though this is role he has been playing for a season and a half, such is the confidence and the realism in the part. I love his stiff upper-lippedness mixed with a great deal of intelligent charm and a streak of pure eccentricity. You can see precisely why Joan is attracted to him from the off.

What's this? A romance in Doctor Who?for the Doctor? I wouldn't imagine Jessica Stevenson as the woman who would capture the Doctor's heart but that's only because of her phenomenal success with Spaced and the lazy character she plays. I have never been more pleased to be wrong; she's superb as Joan, the most successful celebrity guest spot yet. There's so much truth to Joan and Stevenson convinces entirely as the love struck widow, she's quite a serious character (behaving with proper manners as was appropriate at the time) but there are glimpses of humour that make her very charming. The brief admission, "It's been ages since I've been to a dance but no-one's asked me" could sound desperate but from Stevenson's lips it breaks your heart. Think back to School Reunion last year and Rose and Sarah-Jane bickering over the Doctor, the animosity between Joan and Martha (who must desperately try and stand in the way of this romance) is far more gentle. Had Joan been played by a lesser actress this could have been a real nasty character but there is such depth to her that we see a subtle understanding between Martha and matron.

I do hope the rumours about Freema Agyeman are untrue. I love Martha. I have since Smith and Jones. She's a far more intelligent and independent character than Rose, she compliments the Doctor in the same way that Emma Peel complimented John Steed. Even better, Freema is a fresh young face for the series and it is clear that the show has challenged her and driven some fine performances. Human Nature is as much Martha's story as it is the Doctor's and she is inflicted with more indignity than any companion has for a while. The racial comment about her hands made me gasp, it's almost as bad as the assumption that as a maid she should not be familiar with her master and use the side entrance. Watching Martha tip toe around the Doctor is fascinating, trying to cope her best with this hastily improvised situation. The sequence where she returns to the TARDIS is beautiful, like she is coming home. The music during that sequence was particularly good.

Suzie Liggat's first stint as producer is a huge success. The resources she has made possible have resulted in a high-class production with some atmospheric location filming and some authentic sets. The feels of the episode is elegance from the relaxed pace to the depth of characterisation through to the special effects and camerawork. Doctor Who's production values are astonishing these days, truly beautiful and it is pleasing that they can make last weeks dirty, roasting spaceship as classy as this weeks upper class boys school. Certain shots in this episode took my breath away: the light scanning through the field, the scarecrow bursting from the field to attack the little girl with the red balloon, the moody shots of John Smith and Joan walking through the fields.

Harry Lloyd is the spitting image of a young Captain Jack Harkness; should they need to cast the role he would be superb. He gives an interesting performance here, really up himself as Baines but completely chilling (with possibly the scariest alien eyes I have ever seen) as a member of the Family of Blood. He makes a great foil for David Tennant's straight acting John Smith and their confrontation in the final set piece is a quality moment. Many people playing possessed characters use the excuse to ham it up but Lloyd stays on the right side of silliness with his psychotic grin and glinting eyes.

Its another great cliffhanger in a series that seems to have remembered how they work. This one is especially goof because I don't think it is something the series has ever tried before in its fourty year plus history. Such a simple, brilliant conceit?have the Doctor fall in love in an episode and lose faith in his companion and then risk their lives together in the finale. Who does he save? So simple and so effective.

Human Nature deserves the praise that has already been lavished on it, from the papers to the fan reaction. It is as close to an adult drama as the series is going to get without feeling like another series. For one episode the Doctor gets to fall in love, live as a human and lead a normal life. The drama and the potency of that idea are captured beautifully.

After such an amazing opening can I pray that the conclusion isn't a disappointment.

The name's Smith. John Smith.

Back in time again for the third adventure in this memorable season, and a quite-sublime opening instalment of Paul Cornell's two-part adaptation of his acclaimed Doctor Who novel, Human Nature.

Fom the very first explosive scene, this was an absolute treat and, if the concluding episode fulfills the promise on offer here, we could be hailing the finest Doctor Who story of the modern era.

Ironically, that grab-the-audience-by-the-throat opening scene - The Doctor and Martha rushing into the TARDIS pursued by an unfriendly laser beam - while typical of the super-high-octane nature of 2007 Who, was totally atypical of much of the rest of the episode. It was a gentler-paced tale than anything else since the series returned (although Martha kept up her running quotient!). But it was never slow - and totally gripping throughout.

Under threat of death from a race who want to absorb a Time Lord's life span to prolong their own existence, The Doctor could see only one escape route - changing his biological structure for a time until they lose his scent. Using the Chameleon Arch in the TARDIS for the first time, The Doctor became public schoolmaster John Smith in 1913 England, with no memory of who he really was - save for dreams in which he recalled some of his adventures.

Martha is also in 1913, and working undercover at the schoolhouse as a maid. Before undergoing his metamorphosis, The Doctor told her she must instruct him to open a fob watch, which will trigger his memories, and revive the Time Lord within him, if she senses danger, or when three months have elapsed.

Martha realises that the alien family have taken over the body of a maid with whom she had been working, but is horrified to find out the watch is missing - and she has no way of bringing back The Doctor. She's also dismayed to find out that John Smith has fallen in love with a human, the matron Joan.

Meanwhile, schoolboy Timothy Latimer, who pocketed Mr Smith's watch, opens the device, and his mind is filled with images of frightening future events. Another pupil, Jeremy Baines, has been taken aboard the spaceship of the alien family pursuing The Doctor, and his body has also been taken over, along with other members of the village, after being kidnapped by terrifying living scarecrows which are, in fact, soldiers for the aliens.

The possessed villagers track down The Doctor to the local dance and, despite his protestations that he doesn't know what they're talking about, they demand he changes back to a Time Lord - or they'll kill either Joan or Martha.

Even scribbling all that down has one nodding in satisfaction at a beautifully-structured episode, packed with interesting and well-realised ideas.

The living scarecrows were genuinely frightening. We have seen a scarecrow come to life in Doctor Who before, but that was one of The Master's umpteen "I am the master of disguises" in the classic series - The Mark Of The Rani, coincidentally set in a similar time period. The 2007 version - like all monsters in the new series, properly choreographed, were designed to lollop rather than gallop towards their victims, and this was an effective manoeuvre.

Talking of scary, there was a deliciously-malevolent performance from Harry Lloyd as the possessed Baines. Easy to take it into "ham" territory, but Lloyd pitched it right, with the "sniffing" out of his prey liable to send chills a-multiplying through many a viewer.

Almost a given that Jessica Hynes would be a delight as Joan, as she's a superb actress who never disappoints. And more good work from Freema Agyeman who had several interesting exchanges, touching on racism, sexism and classism, all prevalent in the early 20th century. Nothing too heavy, but nicely structured to make the viewer consider the issues.

Star of the show was the star of the show, though. Effectively playing another role - that of John Smith (and for which he was doubly credited) - David Tennant clearly relished the opportunity to show us his range. And, although he seeded in a few Tenth Doctorisms into Smith, this was a delightful and charming portrayal of a 1913 schoolmaster. Tennant's a high-quality operator, and his acting class shone through here, particularly in Smith's warm scenes with Hynes, and his bafflement at Martha's revelation that his dreams were reality.

The BBC are always terrific at period pieces - and really took us back into time with them. Having visited Shakespearean era and 40s New York as well this season, they've been busy bunnies. And Murray Gold proved he can do "restrained"!

I haven't read Cornell's book, but it will be fascinating to compare the original to the TV screenplay. Cornell's basic story is refreshingly different to anything seen in the rest of the series, and it's hard to pick faults with the script. So I won't. Great job.

Nice touch from Russell T Davies, too, naming Mr Smith's parents as Sydney and Verity - respectful acknowledgements to two key figures in the 1963 version of the show of which RTD is so fond, namely one of the programme's creators, Sydney Newman, and producer Verity Lambert.

Nine out of 10, and comfortably the best of an excellent season, which just keeps getting better.

In any other era this story would have been seen as as controversial as The Deadly Assassin (which revealed more about the Doctor's background than ever before, and also, by placing him tangibly among his own kind, portrayed him for the first time as vulnerable, out of his depth and thus more mortal) was in its day, in its radical take on the nature of the Doctor and the Timelord makeup. But in a revamped series already littered with romantic lapses on the main protagonist's part, the radical departure of this episode has had its way softened. Nevertheless, finding the Doctor living as a literal 'human' school teacher in 1913 England, enamoured to the school matron, is still quite disorientating, albeit in a well-articulated and quite moving way.

Before commenting on this highly promising opener to the latest - and most anticipated - two parter of this season, I'd just like to say that I do think the convenient 'chameleon device' the Doctor uses to turn his actual physiology human is a really hard concept to swallow: it seems impossible in theory, as in, how can it actually turn his two hearts into one (which it does of course, as witnessed in the scene when Redfurn checks his heartbeat(s)? Plus, why hasn't he ever used it before? Like when he was fleeing the Black Guardian for instance? This idea really does stretch us from the outset in terms of credibility. However, when an episode is generally as impressive and beautifully made as this, I'm almost beyond caring about the logistics. (One might also now use the concept of this device to argue that the clumsy revelation in the 1996 movie about the Doctor being half-human could be explained by him altering his bio-makeup in order to try and avoid detection from the Master in said story - though clearly in that case he half-botched it...)

This is one of the most filmic episodes done so far and the opening shot of the school to the choiring of 'Yee who would most valiant be' was inspired and reminded me of the classic TV series To Serve Them All My Days. Indeed, Tenant's teacher, Dr John Smith, could quite easily fit the part of said series' cheif protagonist, David Powlett-Jones. 21st century hairstyle aside (they could have gelled it down for this episode really couldn't they?), Tenant very much resembles and acts the part of his disguise, though one of course he has necessarily forgotten to be a disguise, truly believing himself to be the earthling teacher, who is disturbed by strange dreams of time travelling adventures.

This premise is one of the most superb ever thought up for Doctor Who (I know, it's based on Cornell's 90s novel), and in terms of developing the Doctor in a very new way, a truly unique scenario in the entire series' history (a sort of Superman III/Last Temptation of Christ outing for the Timelord). It is handled with great delicacy and feeling here: the romance with Nurse Redfurn is believable, gentle and actually moving, helped by Murray Gold's most/only accomplished music so far, which captures - for once - the mood of the episode. There is none of the adolescent sloppiness of the Doctor/de Pompadour liaissons of the otherwise well-realised Girl in the Fireplace of last year. This is a rather awkward, innocent and abstract love affair (bar one kiss this episode, which too was done believably), perfectly fitting the more sexually restrained Earth period. And for once the Doctor seems to be attracted to someone whom one could conceivably understand him liking: a kind, intelligent woman who oozes humility. The shots of the very convincing and detailed notes and pictures of Smith's time travels are beautifully choreographed, enriching this immaculately realised episode with extra poetic leaven.

The mysterious schoolboy is excellently portrayed, a real Little Father Time (re Jude the Obscure) - if only they'd though to nickname him that, so appropriate too - if I ever I saw one, harrowed-eyed and silently knowing, surely either an alien, a young Timelord, or some sort of younger version of the Doctor? We'll find out next week...

This apparently trapped 'alien' English schoolboy of course is very reminiscent of Turlough in Mawdryn Undead, a story also set in a public school. But what is even more challenging about this episode - and too in common with Mawdryn - is the focus on what might be described as 'the Doctor having a nervous breakdown', as opposed to the Brigadier's literally alluded-to crisis in said Davison story (another case of amnesia). Brilliant treatment of Tenant here.

The elder, Flashman-esque prefect is also an engrossing portrayal, even if he goes a bit too far with some of his lines, overdoing his RP. But he really is a menacing-looking young actor, with his goggling eyes and resonant voice to match. Some shots of him are truly disturbing.

Not so impressive are his two fellow 'family' members and one can't help feeling RTD had a hand in casting them in these roles, echoing his rather childish preoccupation with portly villains (see, well, maybe don't see, Aliens of London). At one point I seriously worried they might have written in those interminable Slitheens into this - that would truly wreck the story.

The scarcecrows! Well, these have to rank as one of the most evocative and creepy monsters ever done in the show (old or New), alongside the baroque clockwork robots in Girl in the Fireplace. Indeed, these scarecrows actually move like clockwork, lurching clumsily forwards with their heads lolling to the sides, a macabre posture duplicated eerily in the humanised 'family'. The shot of the first scarecrow moving its hand on the top of the field is a classic series shot - as are the subsequent rampages. Excellently realised creatures - one wonders why the old series never used such a potent disguise for aliens (the nearest they got was the Master stuffed with straw in Mark of the Rani).

Human Nature does of course have its clumsy lapses (as do all the stories of new Who so far, even the best ones; ie, Dalek (the Doctor with the gun), Impossible Planet (the Doctor's hugging session) and so on): tenuous humanisation plot device aside, we also have aliens firing rather wieldy and cartoon-like ray guns, and a pointless scene in which Martha moans to herself about why the Doctor had to fall in love with a human woman who wasn't her. If this is going to be the extent to Martha's characterisation, I rather hope the recent rumours of her being axed from the series come true (sorry Freema).

But slight quibbles aside, this is a beautifully shot, acted and written episode, and will in time I am certain be regarded as one of the all-time classics in the entire cannon of Doctor Who (though still not quite on a par with Deadly Assassin, Caves of Androzani, Genesis of the Daleks, Pyramids of Mars, Seeds of Doom or Kinda, in my view). But this of course depends very much so on how it pans out and concludes next week! One has grown quite accustomed now to striking first episodes and flatter finales, but I think and hope that with the emotional depth and uniqueness of Cornell's highly ambitious plot, we shouldn't be let down this time.

This season keeps getting better (bar the ok but rather empty filler 42). Human Nature is the best episode of the series so far (and up against strong competition such as Gridlock, Daleks in Manhattan and Lazarus), and arguably of new Who altogether. But as I say, how it concludes next week will very much determine its potentially great status as a complete story. Still, at least we have one episode so far which already achieves greatness in itself.

9.8/10

Now this is more like it; a beautiful, properly-paced old-style adventure that really shows up the frantic one-episode runarounds like 42 and Lazarus as the empty vessels they are - and this story actually has a decent central premise that makes it both unlike anything that's been attempted before, and oddly remensicent of the slow-burning more surreal adventures of early Davison.

A lot of the reason this 2-parter works so well, I think, is that it is finally structured like an old-school 4-parter (so far at least). Whereas some of the previous doubles have just been extended episodes 1 and 4, with the first half all slow build-up and the second collapsing into 45 minutes of frantic resolution, as it stands Human Nature is a perfect tradational 1 and 2, with the scary scarecrows arriving at almost bang-on the half way point in time for what would have been a cliffhanger.

Oh yes! It's all just so wonderful up to that point. The acting, the atmosphere, the delicately woven plotting, the nostalgic nods to the show's past. And just when you think it can't get any better, a bunch of scarecrows turn up and start rampaging about with their own patent Wizard-Of-Oz-gone-bad lollop. There's nothing scarier than animated scarecrows, not even clowns, so why it's taken them so long to mine this particular source of kiddy nightmares is a mystery.

Another important reason this story is such a triumph is that it's just so different. I've recently been bemoaning the profusion of urban-set adventures and lack of anything rural during RTD's reign, and bingo - a little English village, country folk, woodland... I've also been getting a bit bored by the regularity of alien invasions and large landmarks becoming illuminated, so again this is looking very promising in that respect. Only "The Family" themselves feel a bit standard, shooting innocent bystanders like the Judoon and generally over-acting in their first scene (all very high school drama class, the weakest moment for me), chewing their dialogue like any number of other invaders.

While we're on weak moments, the bit with the piano was silly but didn't overtly bother me. Only yet more Rose-based mooning soured the cream a little, but only a little. It passed quickly enough.

David Tennant was at his best yet, playing the likeably vague school teacher with total conviction; the scene with our hero coolly overseeing the machine gun practice, and authorising the young lad to be beaten by his colleagues were chillingly out of character. Two honourable special-mentions for me must go to Spaced's Jessica Hynes, who would make a wonderfully different companion were she allowed to stay on - the most enjoyable companions from the original series were often those from very closeted backgrounds having their eyes gradually opened by their travels with the Doctor; and a straight-laced woman in her mid-30s in the TARDIS would be a delight - and an unexpected left-field treat in the form of Murray Gold's score, not the usual metallic pomp and bombast at all. The strange piece of music which accompanied Martha's visit to the TARDIS sounded like a Burt Bacharach instrumental from the 1960s, while the waltz at the village dance was just lovely. Not to everyone's taste, of course, but I like that kind of thing.

So, on to the references. Nods to the past in Doctor Who have a habit of seeming either crassly smug (the horribly misjudged "new science fiction series" moment in Remembrance Of The Daleks), or just shoehorned in for the sake of it. Here they were perfectly balanced; the nostalgic trawl through memory lane combined with the Doctor-becoming-human plot, this almost felt like what the last episode ever would be like. I'm sure I haven't spotted them all, but these are the ones I noticed:

The biggest reference has to have been Mawdryn Undead: a regular character, having taken a post teaching in an all-boys public school, loses all memory of his past adventures; meanwhile one of the pupils is not all he seems. On the same track, the scene between "John Smith" and the young boy is very very reminiscent of a similar scene towards the start of An Unearthly Child. Then there's the cricket ball stunt from Four To Doomsday. The gag about Gallifrey being in Ireland is a reference to at least one Tom Baker adventure (I forget which). There's a musical nod to Remembrance Of The Daleks with the little girl. And the cockle-warming namecheck for Verity Lambert and Sidney Newman, which could have been toe-curling in the wrong hands. I'm sure there were many others too, and I'm equally sure other reviewers will point them out.

I'm almost nervous to watch next week's episode, I desperately don't want them to blow it. As it stands, I would say this was the best Doctor Who episode since the Davison era, perhaps even Hinchcliffe's Tom Baker years. I'm told this story comes from a spin-off novel predating the RTD era; if so it shows in the depth and richness of the adventure. The only depressing thing is that they could and should have been making stories of this calibre sooner. This is how it's done!

After bestowing praise upon each and every one of the first five episodes this year, last week I promised that I would try to find fault with "The Lazarus Experiment". Whilst the above was said entirely in jest, I did watch this week's episode with a particularly critical eye and, if I'm honest, there were one or two things in this episode that I wasn't especially happy with. On the whole though, "The Lazarus Experiment" is another good, solid episode of new Doctor Who. It may not be up there with some of the 'modern' classics, but it was the best thing on British Television all week by light-years.

I think it was in the pre-season Radio Times where I read that Russell T. Davies wanted this episode to have a 'comic book' feel, and if that is the case then it is a sentiment that has definitely transferred onto screen. Confidential made a big deal of "The Lazarus Experiment" paying homage to the James Bond movies, but tuxedos and gadgets aside, that wasn't really something that I bought into - Bond isn't Bond without scantily-clad women and guns! However, the comic book vibe I did get. The beautiful settings ? first in the Welsh Senate Building ('a laboratory in London') and then in a Cathedral ? both had D.C. or Marvel stamped all over them, and even the characters' names reeked of the genre. Doctor Lazarus. Lady Thaw.

"Ladies and gentlemen, I am Richard Lazarus. I am seventy-six years old and I am reborn!"

Thelma Barlow's role as Lady Thaw was much smaller than I expected after all the hype. Unlike 'Mavis' though, Mark Gatiss was given ample opportunity to shine. The chance to be in his favourite show has been something that Gatiss has waited a lifetime for and, although he might not have been cast in the dream role itself, here he gets to sink his teeth into a quite sinister role that could have been written just for him. Who knows, perhaps it was?

The sparring between Gatiss and Tennant is an absolute delight to watch, especially for someone like me who loves The League of Gentlemen as well as Doctor Who. At times their banter reminded me of how I felt watching Simon Pegg and Christopher Eccleston verbally batter each other in "The Long Game", an episode with which "The Lazarus Experiment" has much in common.

When in prosthetics, Gatiss is indistinguishable from any seventy-six year old man you may see in the street. His voice and his gait also help to get across this elderly, almost grandfather-like character. However, following his transformation I did have a bit of difficulty taking Lazarus seriously ? why in the blue hell did they make him look like Dr. Chinnery? I kept expecting him to stick his hand up a cow's backside!

Richard Clark's direction has to be praised, as does the sterling efforts of the production designers and of course, the Mill. From start to finish "The Lazarus Experiment" is visually spectacular. The C.G.I. in this episode is superb; not just in relation to the obvious but also in relation to some of the scenes inside the Cathedral and even the eponymous experiment itself.

I hope I'm not being too harsh in saying that it is really the effects that carry this episode ? the way the monster's mouth opens outwards; the horrific, calcified remains of it's victims; that breathtaking corridor chase that sees the monster spin around 360? as it runs after the Doctor. Some of the shots in the episode are on a par with some that we saw in "Tooth and Claw". In fact, my only criticism of the effects has to be that the monster's mouth didn't seem to move very well at all with the dialogue ? I noticed that they cut away from the monster speaking very quickly. Nevertheless, such a small detail could not detract from such a first-rate effort. I have a feeling that the Lazarus monster is one destined to be long-remembered. Do you remember the one with??

"He seems so human again. It's kind of pitiful."

This brings me to my main problem with the episode. "The Lazarus Experiment" is a good old-fashioned monster mash, and there is nothing at all wrong with that. However, in terms of plot there seems to be very little going on. Stephen Greenhorn has really made a lot out of the drama stemming from the prescence of Martha's family, but the science-fiction element that is driving the story is very simplistic indeed. Greenhorn may touch upon Lazarus' reasons for wanting to live forever, but his back-story is rather predictable and, if I'm brutally honest, dull as dishwater. Gatiss deserved better, really.

That much said, Greenhorn really hammers home the mysterious Saxon's hand in all this. If the rumours about his identity are true, then his interest in Lazarus' work is hardly surprising considering how he has always desperately clung on to life in the past. Looking back on this episode at the end of the season, I'd be very surprised if - as was the case with "The Long Game" - it did not come to light that there was much more going on here behind the scenes. As a stand-alone episode though, I have to say that the story feels distinctly lacking.

"A longer life isn't a better one. In the end you just get tired. Tired of the struggle. Tired of losing everyone that matters to you. Tired of watching everything turn to dust. If you live long enough, the only certainty left is that you'll end up alone."

But as I've said, what this episode lacks in storyline it more than makes up for in spectacle. The final showdown inside Suffolk Cathedral is a thing of beauty in so many ways. The Doctor's eloquent speech. The near-religious imagery of Lazarus naked in the shroud. The Doctor's nod to Spinal Tap: "We need to turn this up to eleven..." Martha hanging from the bell tower. Fantastic!

Looking at the larger story arc for a moment, "The Lazarus Experiment" marks something of a watershed for Martha Jones. It sees her return home for the first time since she begun her travels with the Doctor, and it also marks the first appearance of her family since "Smith and Jones".

"He's dangerous. There are things you should know."

In direct contrast to his navigational cock-up back in "Alien of London", here the Doctor actually gets Martha home within twelve hours. He still manages to earn himself a slap from Mrs. Jones though - "All their mothers. Every time!" ? as throughout the episode she has some sort of 'secret service' bloke whispering in her ear about the Doctor and how dangerous he is. Even so, I think that in this episode Francine comes across as very unlikeable - I can certainly sympathise with Martha's Dad! Even in her fiercest moments, Jackie Tyler was always loveable. Adjoa Andoh portrays Francine as much more austere; a much tougher nut to crack in many ways.

"I know the age thing's a bit weird but it worked for Catherine Zeta Jones."

Martha's sister Tish is also given quite a bit of exposure in this episode, and whilst she is not as severe as her Mother, she comes across as a bit 'up herself' and even a bit shallow. Prior to Lazarus' transformation, Tish won't even give him the time of day, yet as soon as he becomes a handsome young(ish) man, she's all over him! However, it is important to note that at the end of the episode she's there for Martha to catch her when she falls. Literally.

Of the Joneses, only Leo acquits himself as a pleasant, well-adjusted young man, though I suppose it's early days! Jackie, Mickey and Pete really endeared themselves to the audience over the course of the first two years and so I think that the Joneses have a difficult task in trying to replace them. So far, so good though.

I enjoyed the final scene very much. It sees Martha become a 'proper' companion as opposed to a mere 'passenger', much in the same way that Rose 'signed-up' properly at the end of "World War Three." "Okay," says the Doctor, nodding towards the open TARDIS door. "Well, you were never really just a passenger were you?"

And so off they go; off into the forty-second century.

"I'm begging you. I know who this Doctor really is. I know he's dangerous; you're gonna get yourself killed! Please trust me. This information comes from Harold Saxon himself. You're not safe."

On a final note, I'd just like to say 'bloody Eurovision!'

I suppose if you do have to stall the season for a fortnight, then this semi-cliffhanger is a tantalising way in which to leave things, especially when combined with the new Christmas Special-style trailer for the rest of the season. It seems that there is certainly much to look forward to ? Captain Jack back in action; Saxon in an oxygen mask tapping the desk, evilly; a dark and gritty 'real time' adventure out in space; not to mention the "Human Nature" dramitisation. I haven't read the novel for a while, but I don't remember Scarecrows or a Wedding! They certainly seemed to have jazzed it all up a bit for TV, even the Aubertides look far more threatening on screen than I imagined when reading the book.

"He's fire and ice and rage? Loves greatly, but not small-ly. He's Merlin."

Roll on Saturday week!

I wasn't particularly looking forward to this episode to be honest: all-too-obvious mad scientist plot with all-too-obviously named professor, return to Earth, reappearance of plastic Martha's plastic family, CGI monster and so on. All the ingredients for the kind of irritation, boredom and cringing I normally experience during your average New Who episode.

But I was pleasantly surprised by The Lazarus Experiment. Of course it still had token annoyances which have become something of the RTD production-tradition now, but this particular story managed to rise above such irritant factors due to a general seriousness of tone and a well-articulated - albeit not entirely original - plotline.

From the outset, boundaries were being put down by the maturing Doctor towards his latest and rather simpering companion, Martha: for once we had a reason, more like the old days, for the Doctor to return his companion to her time on Earth: he wanted to call it a day and put her back we he found her. And who can blame him? Martha is even more insipid than Rose, but seemingly lacking the latter's attempt at a personality. Martha seems to have none at all. Her fancying the Doctor just seems substanceless and token in its doe-eyed vapidness. There's no chemistry at all anyway. So I thanked God that the Doctor started this episode further emphasising his emotional detachment from her. If only she hadn't hopped back on at the end (but that was his fault admittedly).

This scene also adds a welcoming touch of alienness and detachment to the rather erratically scripted 10th Doctor, and this is greatly welcome. This slightly restless and solipsistic slant on Tennat's incarnation is also nicely reminiscent of early Pertwee's misanthropic fuss-pot of a Doctor, who had childish tantrums whenever his attempts to regain control of the TARDIS for purposes of self-centred escape from his rather mundane UNIT trappings backfired.

This is, in many other ways, very much Pertwee-era territory (sonic screwdriver aside): the 10th Doctor, just like his ever doomwatching 3rd incarnation, pops along - in tuxedo too - to witness the latest amoral experiment turning heads in the human scientific community. In this sense this episode is very reminiscent of the enthralling thriller of Season 8, The Mind of Evil. We also have the ultimate fan reference to the 3rd Doctor: 'reverse the polarity of the neutron flow'.

What I liked the most about this episode wasn't the plot itself, but certain concepts and chunks of explanatory monologue from the Doctor, which added real leaven to what could have otherwise degenerated into a facile run-around. The suggestion that the regenerative process of Lazarus's machine should produce an atavistic reaction in the human body, tapping in to an evolutionary cul-de-sac wherein our genes still contain an aborted DNA chain which could have led us to evolve into scorpion-like insects rather than apes (and then humans), was the stuff of classic Who, and really did add terror to an otherwise ambitious but only half-convincing CGI monstrosity (the body was good, but the air-brushed-on face really didn't work for me, and just looked like a computer graphic, and also not remotely like Gatiss himself) - I think CGI should be scrapped entirely now, and more tangible model work should be employed: the similar man-headed spider creature in the Eighties version of The Thing for me is far more convincing than The Mill's efforts nearly a quarter of a century later.

But what really carries this story is the consumate performance from Mark Gatiss in the title role. In Professor Lazarus, we have, in my mind, the first really charismatic and affecting foil for the Doctor since the new series began. The character is in some ways reminiscent of Julian Glover's immortal turn as Count Scarlioni in the classic City of Death. And of course Gatiss is well aware of his classic lineage in this regard being an out-of-the-closet Whovian himself. He pulled out all the acting stops in this episode, in quite the opposite fashion to how 'Trigger' pushed them all into ham as Lumik in Risable of the Cybermen last year. Gatiss shows how a Who villain should be done: with suave menace and a subtle hint of self-torment. But where Gatiss's performance, and indeed the entire episode, really comes into its own, is during the cathedral scene, as Lazarus cowers in mutating pain naked in a red towel on the flagstones, in a battle of philosophies with the Doctor. This scene was exceptionally well-directed and acted: darkly, subtly, but above all, dramatically. This scene also reminded me a bit of the 5th Doctor's final confrontation with the mutating Omega at the end of Arc of Infinity (and is it just me, or does the young Gatiss bear a vague facial resemblance to Peter Davison?). During this scene also, there is a pivotal and highly resonant retort from Lazarus to the Doctor's comparatively superficial observation of how 'facing up to death is part of being human' - which of course is imutably true; but Lazarus comes back with an equal truism about our contradictory condition: that it is also our instinct to 'cling to life with every fibre of our being' (sic). Even the goggle-eyed 10th Doctor seems struck dumb by this statemtent. Excellent scripting. Here then we have a tale suitably grisly and morally-disturbing as its obvious literary influence, Dorian Grey.

The only trouble that crops up here is that Gatiss frankly steals this episode from Tennant - and though Tennant strains to rise to the occasion - and doesn't do too badly in places -there is no doubting in my mind that this was one occasion, and actually probably only the third of three occasions for me in the show's history, when an incidental actor in a Who story seemed to have 'Obvious Doctor material' stamped all over him in comparison to the current incumbent (the other two occasions for me were Paul Shelley opposite Davison in Four to Doomsday, and David Collings opposite Davison (again, sorry Peter) in Mawdryn Undead). I know Gatiss has long nursed a fantasy of one day playing the lead - partly pampered to in his comedic cameos in the 30th Who anniversary documentary), and this is a potential I haven't been convinced of myself previously. However, on the basis of his turn in this episode, I did feel instinctively that he was more obvious Doctor material than Tennant. In his very RP, throaty delivery of lines, Gatiss oozed the kind of old-style theatrical gravitas that has so long been missing from the Timelord's interpretations. As the young Lazarus, I detected also a passing resemblance to the young Derek Jacobi (turning up of course soon in Utopia, which is tops with me, being a massive fan of I,Claudius, especially of Jacobi's eponymous performance).

The musical extermination of the Lazarus monster was indeed 'inspired' as the Doctor put it - and the sight of him grinding away at the church organ as a means to defeating one of his foes has to surely be one of the most, well, artistic ways in which the Timelord has ever won the day. Definitely inspired.

Subtle hints at the inevitable identity of the mysterious Mr Harold Saxon aside, the other key factor of this episode which I think deserves particular mention and praise, is that for practically the first time since new Who began, we have the Doctor finally using a more erudite and profound cultural reference properly befitting the drama of the occasion than bathetic trendy allusions to Kylie Minogue lyrics or third-rate Eighties films: 'not with a bang but a wimper - Eliot. I also liked the subtlety here of saying 'Eliot' rather than 'T.S. Eliot' - not even spelling it out. This was a truly welcome return to the more profound and poetic days of the glowering 4th Doctor (cue his tendency to quote poetry, as in The Face of Evil and at the end of Horror of Fang Rock). Again, brilliant scripting. And what a polar contrast to the usual contemporary cultural allusions.

To sum up then, this episode certainly didn't go out with a wimper, as I was starting to suspect it might about 10 minutes before its end, with a red-herring conclusion of Lazarus being stretchered away in an ambulance - but the episode hit back with a real vengeance and a philosophically challenging denouement which in itself (that cathedral scene) will, to my mind, go down as a classic moment in the series (both old and new).

Like Gridlock, another pleasant surprise of an episode, The Lazarus Experiment continues to show how unpredictable this season is turning out to be. This is not necessarily a classic story, but it certainly contains some unexpectedly classic moments, which is the next best thing. Mr Gatiss, I'd hand you the keys to the TARDIS any time.

7/10.