There's an old tradition when it comes to two-part storylines on "Star Trek". The writers spend so much of Part One setting up for an amazing cliffhanger, that Part Two almost always feels like a let-down. Before seeing tonight's episode of "Doctor Who", part of me was thinking something similar might happen here. Well, I'm pleased to report that "Doctor Who" has not travelled the same path as "Star Trek".

Russell T Davies returns with a very good script, full of some classy one-liners and the usual wit we have come to expect from his pen. Thankfully, Russell doesn't rely on wit alone to carry the story. The sheer scope of events is magnificent, with some serious dramatic tension on the line here. There's also some nice touching moments, especially as Jackie tries to come to terms with Rose's relationship with the Doctor.

As I suspected when I reviewed 'Aliens of London' last week, the overall story arc doesn't move along very much at all. In fact, aside from a slightly humourous bit at the end (bringing closure to the graffiti bit in 'Aliens of London'), there's no mention whatsoever of any of the "bad wolf" or "time war" elements already mentioned in the series. Which is no bad thing, I must admit. Makes for a nice change.

Christopher Eccleston and Billie Piper continue the tradition of this series, with both of them giving very good performances. Billie really seems to be shining in this series, and is making every effort to silence whatever critics she might have left. Christopher, meanwhile, is obviously enjoying the role, and the wide variety of challenges that it asks of him as an actor. The scenes these two share are wonderful to watch.

The guest cast is generally the same as last week, with some rather fine performances from all involved. It was indeed nice to see the slightly larger members of the British acting community getting a chance to sink their teeth into some meaty roles (no pun intended). Of the guest cast, Penelope Winton comes off best, with her portrayal of Harriet Jones being perfect. It was also nice to see Camille Coduri and Noel Clarke once more.

The production values continue the high standard of Part One, but its obvious why things look so good in this particular adventure - all the sets in 'World War Three' are the same as those featured in 'Aliens of London', and its clear the money has been well spent. It was a shame more wasn't made of the team's visit to the Cardiff Royal Infirmary, as I'd hoped that impressive location would end up being used more often.

Special effects-wise, the episodes come off quite well. There's a wonderful balance between costuming and CGI for the Slitheen (although some of the CGI shots featuring the Slitheen looked a little too fake), while Mike Tucker's impressive model work comes into play once again as the episode ends, and the script calls for 10 Downing Street to be blown up! Nicely handled, and it made for an explosive end to a very good episode.

As this is the final episode to be directed by Keith Boak, part of me is sad to see his contribution over (he was, after all, the first director on the new series), but it means that we've finally moved past the first block of filming, with all its inherent problems. Things can only go up from here. Finally, Murray Gold does his usual impressive piece of work on the episode, although I spotted some re-use of cues.

Overall, 'World War Three' brings the new series' first two-part storyline to a spectacular finish. I suspect in future years this particular two-part adventure won't be held in the same high regard as the original series classics like 'Caves of Androzani' and 'The Talons of Weng Chiang'. It is, however, still an impressive piece of work, and should be celebrated for pushing the boundaries of British TV.

Overall Score: 5 / 6 (Very Good)

According to Doctor Who lore, 'K9 and Company - A Girl's Best Friend', was intended to be a pilot for an ongoing spin-off series featuring the eponymous robot dog, and accompanied by other former companion Sarah Jane Smith. Watching it again however, I can't help feeling that what actually happened is that John Nathan-Turner said to his superiors something along the lines of "You want a Doctor Who spin-off featuring K9? Well before you commit to a full series, let me show you just how badly it could turn out…"

To be fair, whilst fans have long debated the subject of whether or not Doctor Who is a children's programme, I think I can quite safely describe 'K9 and Company' as a story aimed at the younger members of its parent series' audience. Possibly children who are still reading Enid Blyton's Secret Seven books, in fact. With a black magic coven in a sleepy English countryside village, the plot of 'K9 and Company' manages at the same time to be both ludicrous and dull. The moronic portrayal of witchcraft bears so little resemblance to any real pagan religion of which I am aware that it makes the Master's coven from 'The Dæmons' look convincing. Naturally, the members of this coven are superstitious country bumpkins. As if all this wasn't bad enough, there's actually very little of interest going on within the confines of this already dubious plot. There is an attempt at misdirection by writer Terence Dudley, who tries, with reasonable success, to divert suspicion from the gruff but likeable Commander Pollock, and towards innocent couple Juno and Howard Baker. Amusingly, this means that Howard Baker ends up seeming creepy early on in the story for no actual reason. Aside from this however, everything is painfully obvious and straightforward, with almost every other inhabitant of Morton Harwood seemingly prepared to participate in murder out of fear of Hecate.

This derivative and unconvincing drivel could have been saved by the combination of K9 Mark III and Sarah Jane, and to be fair, Elizabeth Sladen falls back into her old role with ease, perfectly reprising the character of old. The problem is, the character of old here appears to be written as a poor man's Mrs. Emma Peel, thanks to Sarah's newfound martial arts skills and the fact that she is basically dealing with lunatics in a pleasant English village. It isn't that Sarah is written out of character, just that the script feels so half-hearted that it seems to have been weakly inspired by numerous other sources and lacks originality. K9 might perhaps be expected to add a more distinctive feel to the proceedings, but incredibly, he's barely used. Possibly due to the limitations of the prop on location, K9 spends most of his time trundling around Aunt Lavinia's house, either spouting expository dialogue or acting as a mobile gun. The finale, in which he knocks out more or less the entire coven, really emphasizes just how banal the whole thing is; Dudley seems to have been unable to get past the issue of K9 being too powerful, often touted as the reason for John Nathan-Turner deciding that K9 should leave Doctor Who. Consequently, all K9 really does here is wait until the end and then shoot the villains. His other scenes are entirely padding, even his deductions about the plot already nearly reached by Sarah or Brendan. Despite the story's title, this is not a story about K9, it is a story about Sarah Jane, who as Big Finish have demonstrated is a character with enough potential to carry her own series. K9 is there to pitch the story at a young audience, and so in addition to one of the single most embarrassing title sequences of any television series that I have ever seen, we have the dull "comedy" of K9 quizzically approaching a garden gnome and accidentally breaking a greenhouse as a result, and K9 attempting to sing "We Wish you a Merry Christmas" at the end.

Aside from all that, there is very little else to say about 'K9 and Company'. The location filming and the studio sets both look nice, and John Black competently if unimpressively directs the story. Of the guest cast, Bill Fraser is quite good as Commander Pollock and actually seems to be making more of an effort here than he did as General Grugger in 'Meglos'. Also worthy of note is Mary Wimbush as Aunt Lavinia, who brings to mind Beatrix Lehmann's Professor Rumford from 'The Stones of Blood', and Ian Sears as Brendan who acts with an enthusiasm that suggests that this is his first television work. The rest of the cast vary from those who are reasonable enough but seem to be acting on auto-pilot (Linda Polan and Neville Barber as the Bakers), to the plain awful (Sean Chapman as Peter Tracey). Ultimately, 'K9 and Company' is a failed experiment and, perhaps, a wasted opportunity.