This review contains spoilers and is based on a standard, non-binaural preview version of the episode. 

Speaking at the BFI/Radio Times TV Festival last month, Steven Moffat remarked that one thing he'd like to do after showrunning Doctor Who is write a play. Moffat has done his bit for trafficking between the worlds of theatre and TV talent this season, however, by securing the services of both Rona Munro and feted playwright and Doctor Foster creator Mike Bartlett. King Charles III, one of Bartlett's recent and highly successful plays, is about to hit our television screens in an adapted version, whilst 2016's Wild -- a piece based loosely on the Edward Snowden case which took a radical turn into almost Who-esque territories -- has shown Bartlett's affinity with relevant material. Now, it would seem, is very much Mike Bartlett's time to clamber aboard the occasionally creaking but always smartly veneered Whoniverse.

Knock Knock is, let's face it, a rather cheesy title, gesturing at those repetitive old "Who's there?" jokes that probably still generate endless amusement among the programme's youngest fans. But by giving this reference an adult spin -- for this is a riff on the venerable haunted house subgenre -- Bartlett cleverly blurs together child and adult sensibilities right from the outset. Playing with the Doctor's relationship to Bill, and having her address him as "grandfather", is also a lovely throwback to the 1960s show; I initially responded to it in exactly this manner, as a gift to long-term fans. But cunningly, it also slots perfectly well into the theme of this episode's eventual and familial denouement, a smart tongue-and-groove piece of thematic construction (and generational confusion) that's hidden in plain sight.  

Writers new to Who have a tendency to emulate the leading tropes of their commissioning showrunner -- Matthew Graham's Fear Her often felt like RTD-lite, and Stephen Thompson's The Curse of the Black Spot replayed Moffat's favoured device of 'technology gone awry'. Here, we get an aspect of the ordinary, everyday world transformed into a fantastical threat, something which, though it has an extensive history in the programme, has also become part of the Moffat repertoire. And there's a kind of variant take on "are you my mummy?" which harks all the way back to The Empty Child/The Doctor Dances. Having said that, Bartlett doesn't only seek to fit seamlessly into the Moffat-esque way of things, and also stamps his own mark on proceedings, notably in a comedic sequence criticising the state of students' rental accommodation in the UK, albeit imparting its critical stance with a deftly light touch.

On the minus side, I felt that Bartlett was sometimes a little cramped by the demands of a 43-minute single episode when he's evidently used to working with longer dramatic forms that have more space to unfold characterisation (something that the serialised Doctor Foster achieved quite brilliantly). Since the haunted house story calls for a number of characters who can be bumped off, Bartlett is also pretty much obligated to give Bill a decent number of housemates. This immediately causes a difficulty because each one threatens to become a student stereotype or a single-note creation. Perhaps slightly fewer students to be menaced by Wester Drumlins -- sorry, Bill's new residence -- would have helped on this front.

The tightly-coiled demands of an episode that has to set up atmospheric menace before delivering a pay-off 'reveal' also make life slightly difficult for guest star David Suchet, who is required to oscillate between ordinary-but-odd, outright creepy, and something far more essentially and basically human. It's a tough ask, and in places Suchet's performance seemed a little too mannered to me. But regardless of that, Doctor Who is fortunate to attract actors of such calibre, and I was admittedly disappointed that fan speculation regarding 'the Landlord' (that he would become a recurring character of some mysterious and Time Lordly status) fell wide of the mark. Suchet's character is very much a one-shot, belonging to this story alone. 

 

Series 10's Vault storyline continues to gather pace, and the concluding moment -- withholding a reverse shot that would have revealed who was in there -- was deliberately cheeky, and all the more effective for it. But an episode entitled Knock Knock is bound to rely, more than most Doctor Who, on its sound design and soundtrack. On the whole, this worked very well, though the level of aural threat could perhaps have been more intense (I'll be interested to see whether advance hype surrounding this as a very scary episode is reflected in the general fan and audience response, as well as how much difference the binaural version makes). I'm a horror fan, but for my money this was far stronger on atmosphere and build-up than any genuine sense of shocks, jumps or 'scares'. The monsters' mass presence was, in the end, effective without being remarkable -- we dodged a Tractator-level incident, to be sure, but all the CGI hordes still felt generically competent rather than truly memorable.

 

And packing an episode with wood-related content is, I suspect, always going to be a risk in terms of inciting reviewers' puns or provocations (you can just imagine how any journalist looking for a punchline would reach for their finest grain of 'wooden' material). Actually, focusing on this dimension -- something that has rarely featured in Doctor Who other than as a challenge for the sonic screwdriver -- gives this episode a very specific and quasi-historical flavour. Yes, it's a present-day story, but instead of brutalist concrete-morphing creatures, steel-and-chrome monstrosities, or electronic/nano-techno-villains, there is something almost pleasingly quaint, if not retro, about a good, old wood-based threat. There's a sense of sedimented history, and the dust of ages, that setlles over 'Knock Knock', making the eventual reveal of Eliza's presence (and identity) an integral part of this 'return of the repressed past'.

Knock Knock does what the best of contemporary Doctor Who has always strived for: it combines fantastical threats with social commentary and moments of touching emotion and humanity, at the same time as fusing 'child' and 'adult' levels of meaning. As the proverbial 'family television' it also uncovers a gothic, dysfunctional family -- one that needs to be fixed by the Doctor's intervention. Holding on to the past at any cost is shown to be a powerful mistake, and 'Knock Knock' is ultimately about a very different kind of fear to its earlier evocations of creaking floorboards and unseen forces, zeroing in on the fear of loss, and all the misguided actions it can provoke, rather than notching up a villainous case of megalomania or 'evil'. In this, it marks its distance from certain previous incarnations of the show, and develops an approach highlighted in The Pilot. But the question that remains, given the Doctor's chatty engagement with the Vault's occupant, is whether he too, like the Landlord, is mistakenly holding on to an aspect of the past... In a week or two, we'll start to get some answers. 

NB - This review contains a plethora of spoilers (based on a Preview Edition of the Episode).

However, warning signs have (barely visibly) been laid out, so as to remind people of the ice being less sturdy in certain regions. And this is with good reason. People have begun to disappear, and it would appear there is a connection to some un-natural green lights that can be seen through the frosty surface.

Eventually the Doctor and Bill have to investigate in-depth, and some hard truths come to bear. For the first time, their relationship faces a test. But perhaps in facing a very human, very cold, monster in the form of Lord Sutcliffe, they can continue to function as a partnership of universe-weary wisdom, and fledgling careless brilliance.

This story continues to see the 2017 sequence of Doctor Who in fine fettle, and assure viewers that soon-to-depart Peter Capaldi is now producing some of his best form (as opposed to phoning it in for a nice pay check and exposure via prime time scheduling). By now it is standard practice that the first two adventures proper for a companion of the Doctor, after the season opener, see a quick succession of the past and future. (The order tends to fluctuate, depending on the season in question).

With these second and third episodes, at least there is a small change-up, utilising the secondary companion (as played by a confident Matt Lucas). The framing device of Nardole scolding the Doctor for going off world - which indeed is true for the events of Smile, if not technically this third adventure - is nicely done, and also includes a hint of what the Doctor and his part-robot-part-humanoid friend are guarding back in Bristol.

Sarah Dollard came up with a wonderful debut story last series, and provided a most memorable official demise for Clara Oswald, with Face The Raven. This story is not quite up on the same level, and continuity-wise is not a game-changer. However, the many virtues of world building and characterisation are all present and correct, once again. Virtually all the on-screen players who end up as nutrition for the aquatic alien being are sketched out effectively - even if they have rather limited screen time to work with, due to the primary character development being devoted to our two regulars.

This episode often makes no attempt to hide how it takes inspiration from previous stories in Doctor Who's lore. The Doctor advising Bill how to get to the wardrobe is a reminder of (the un-transmitted but frequently adapted) Shada. After the Doctor and Bill begin their explorations proper, the TARDIS pinpoints the size of the being under the ice, and also how much danger it poses, which is a faint echo of the ending moment of 1963's very first Who serial. More recent use of past convention is found in the use of the sonic screwdriver and psychic paper, with the former in particular driving the earlier parts of the story forward. 

Possibly even more so than prior episodes this year, the main heart of Thin Ice lies in the Doctor and Bill continuing to establish a working partnership together. Whilst the Twelfth Doctor noticeably ‘softened’ over the course of Series Nine, he still retained some darker edges, and these are particularly conspicuous at times. The cold manner in which he retrieves his sonic screwdriver from both the doomed Spider, and later one of Sutcliffe's thugs, leaves Bill repulsed and shocked. Noticeably she feels horror, irrespective of the actual personal qualities of the person who could not be saved from their fate.

The Doctor also deciding to be far more mysterious (certainly when compared to his Ninth and Tenth incarnations) over how he has had to make difficult choices when saving people, and also when to kill, is a very nicely-played scene by Capaldi and Mackie. True, it could easily appear in any given episode at any opportune time, and is not necessarily dependent on the story surrounding it. But it still is fine work from the writing/production team, and of course the main praise should be reserved for our two lead actors.

And in general, the Doctor is showing hints of his rather less personable qualities, which most of us have come to associate with his maiden season in 2014, rather than the somewhat breezier persona that crossed the airwaves on a weekly basis two autumns back. He is blunt to Peter Singh's 'Pie-Man' on their very first meaning, going so far as to undermine the legitimacy of the man's livelihood, back in a time of Earth history where ethics and truth did not have the same priority they do today. And whilst it is meant to be humorous for the audience (in a very knowing Roald Dahl fashion), his description of the lost children as being on the "menu", is indicative of his grim acceptance that the alien being simply is higher on the food chain than humans, regardless of whether it should belong in the Thames river in the first place.

But there are plenty of lighter/warmer sides to our title hero too, with the mention of a magic wand being a reminder that whilst Doctor Who is officially a sci-fi show, in many respects it takes sustenance from traditional fairy tales and legends. The very first actor to play the role on TV, William Hartnell, once described the main character as a combination of a Wizard and Father Christmas, and his point still stands many years down the line. Also, the quiet little scene as the Doctor tells a 'bedtime' story to some of the orphans is beautifully played and directed. Suddenly the moral dilemmas are secondary, and all that matters is a wise man with grey curls, presenting a narrative with conviction and gusto.

Come the end, as the remaining survivors find themselves fortunate to have a wonderful new property in which to live, there is a knowing look from the Doctor and Bill acknowledging that the deeds must be in the name of a male heir. Yet if the time-travelling genius could bend the law and change history to allow the charming Kitty to have the privilege of being the next in line, then he would. It is a moment that has huge impact on anyone with a semblance of heart and soul in them.

Bill continues to put hardly a foot wrong, whether in terms of connecting with the audience or being acted authentically by the (comparatively inexperienced) Pearl Mackie. Along with other examples given here, there is a lovely moment where the Doctor's favourite student is overcome with wonder that she can walk on the Thames. Whilst the famous river is a great visual motif, it is also not associated with being crossed without the help of a vessel, and is heavily polluted. Later, when it is made clear what the villain's key motivation is in terms of the energy source he is obtaining, a very funny (if naughty) joke is made as Bill reacts point-blank. The full phrase would not pass the censors for a show like Doctor Who, even if movies shown even earlier on other TV channels get a free pass, but by being so coy in doing a quick edit, the effect is markedly pronounced. (And furthermore, another continuity echo is made, in terms of Rose teasing Cassandra, back in Series Two's opening story). 

The ending of the story is probably the most fully satisfying for the show in some time, with perhaps the last such occurrence being the conclusions of Heaven Sent and Hell Bent. Whilst perhaps simplistic, it is elegant and uses the decision to give just enough explanation via rapid editing, and travelling forward to the present day, with an archive newspaper article being knowingly referred by the Doctor. He often realises that sometimes an abridged account of the whole truth is for the best. That the ostensible monster of the story is not judged guilty of any wrongdoing, and is merely manipulated by Lord Sutcliffe, is welcome too. And show runner Moffat clearly has decided to steer away now from the overused 'everyone lives' trope. The good, the ambiguous, and the dastardly all firmly remain dead and buried. Thus, the Doctor's quiet admittance to Bill of the limits of his power to save people is not compromised in the final stanza.  

The episode also looks very impressive. The scenes underwater are built up to in a suitably suspenseful manner, before the efficient SFX work comes into play, accompanied by some of Murray Gold's best use of more subtle musical dressing. This ensures the core of the story is strong. Sometimes going into the murky depths of the aquatic can be a pace killer, but not here thanks to the decision by Bill Anderson to emphasise mood and uncertainty in the earlier sections of the story.

Elsewhere on ground level many extras are used, along with ‘convincing’ animals in the background, and props galore. There is a sword swallower, some play fighters, and countless other novelties. Never for a moment does it not feel like the capital city of England developing at a fast knot, back in the time of the Regency era. 

So far, the show has done fine work in establishing who Bill is, by giving her plenty of character and plot-relevant material, this latest instalment very effectively addresses her attitudes to sci-fi itself, and more significantly to her identity as a woman with a mixed ethnic background. The character material on Bill being something of a sci-fi fan herself is mostly played as light-hearted self awareness, which is so indicative of Steven Moffat’s general style – both in Doctor Who and in his many other TV (and film) projects over time. Asking the Doctor to clarify if they are on a parallel world, and just why he calls his sonic screwdriver that name are amusingly played out in dialogue.

However, the more worthy focus on attitudes of mankind concerning 'race' is made into a significant part of the story. Having the Doctor and Bill trying to integrate as best they can feels more important than in other episodes where the setting is simply pure fantasy/ sci-fi in nature. For the young lady from the 21st century England, there already is likely one too many a memory of being treated as inferior for the way she looks. To suddenly be back in her own country at a time when slavery was acceptable (be it of women, foreigners, those of 'other races', or even children) is a major jolt, and she immediately makes an effort to dress up so as to fit in, but clearly wishes this was not a requirement. And of course, eventually even that change of attire is not enough to stop a bigot from verbally abusing her.

The man in question is Lord Sutcliffe, and this main villain for the episode is not a pleasant person in many respects. He seems utterly without empathy, and has a detachment about his overall operation, even if the end result would see him become richer (and thus more powerful) still. However the denigration of his ‘inferiors’ who do not share ('enough of') the same bloodline as him remains the most deplorable aspect. Whilst the Doctor and Bill manage to set time 'right', the story very quietly yet noticeably makes a point that the evil of slavery is something mankind must realise over time is wholly wrong.

I have few real complaints with the basic narrative. It does in principle echo many episodes of yesteryear – something probably inevitable given how far the series has been in existence – but is never executed in anything less than an enthusiastic manner. Nonetheless, a general issue I have had with Series Ten again crops up here. We have at least one moment for the audience being ‘spoon-fed’, when the distinctive hat of Spider (the thieving little boy who could not be saved) is seen as rejected by the monster in the depths of the Thames, along with quick flashback of his thieving of the sonic device the Doctor so prizes. 

This reminded me of the repetition used concerning Heather meeting Bill on a night out, when the original image was already striking enough in how it was shot to resonate with the viewer. Perhaps though, exposition and clarification of the mystery does not quite verge on being so heavy-handed, as during the scenes in Smile where the TARDIS duo found out the whole truth behind the dilemma they were presented with.

I mentioned Sutcliffe as serving the themes of the story well, but as an actual genre villain, he is rather middling overall. Whilst certainly played competently by Nicolas Burns, in that the audience is made to firmly dislike him, he also is very much out of his depth. The screen time afforded him is neither used efficiently enough to give us truly involving motivation and back story, nor abundant enough for him to be memorable in the viewers' minds after the episode has concluded. Sutcliffe's henchmen are never made into anything too chilling or threatening, but still have enough dialogue and commitment in the performances to convince viewers that they could have come from the criminal underworld, and are making the most of an employer with more money than most others. Dollard still does fine work with the villains, in terms of presenting the more corrupt and deplorable aspects of British society at the time, where gaps between the so-called upper and lower classes were wider than any cracks in the river's ice.

However, the performances of the children are uniformly terrific, which is pleasing to see after Smile had a winning turn from Kaizer Akhtar. When the Doctor needs some exposition from the locals, it is the orphans who whole-heartedly give him the information he requires, and the story smoothly advances as a result. Furthermore this authenticity of portraying urchins who barely are able to keep themselves fed really helps the end of the episode.

As the alien creature emerges from its 'prison' and is displayed in full, top-quality CGI glory, there is a great moment as Bill admires how it looks and is able to forgive it for being a killer. But the best part of the satisfying resolution is seeing the Doctor restore the barely surviving orphans to a place of safety – one far grander than any could have dreamed of. The wink in the eyes of both the Doctor and Bill as they turn the class expectations topsy-turvy, really helps this become a ‘punch-the-air’ moment. And it would not have been nearly so effective, if the children had not been as fully breathed to life in the performances by these youngsters. 

As good as our leads are here, and I expect even better work in the ‘bigger’ episodes to come, the main praise should be reserved for the quintet of Badger Skelton, Asiatu Koroma, Austin Taylor, Kishaina Thiruselvan, and Ellie Shenker.

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OVERALL ASSESSMENT:

Series Ten's third individual story stands up well, as a very enjoyable outing in the early 19th Century. It is thoroughly watchable, whether the viewing takes place on a Saturday evening (as per tradition), or via a streaming device that does not have to be fixed down in a given time and place (like the TARDIS herself). And the icing on the cake? A snappy preview that sees the definitive Poirot actor – David Suchet – making a guest appearance, to potentially lend the hyperactive Time Lord some pearls of wisdom.