In Knock Knock, Bill Potts (Pearl Mackie) moves into a house with some of her new-found friends from university. This place is not your average set of student digs and is instead like something the Addams Family might favour. Before too long, it starts ‘eating’ people and it’s at this point that the Doctor (Peter Capaldi), who has already sensed that there is something not quite right, springs into action.
Knock Knock seems to have gone down well with most people, if online reaction to the story is anything to go by. This shouldn’t be a big surprise. It features good performances from both Capaldi and Mackie, has a wonderfully creepy turn from David Suchet as the Landlord, and is well-directed by Bill Anderson: a spooky, claustrophobic ‘haunted house’ yarn in which, at first, the house itself seems to be the monster rather than any ghost or ghoul.
I think this was another solid episode in a season that may well go down as one of the best since the return of Doctor Who in 2005. I’ve already mentioned the performances of Capaldi, Mackie, and Suchet. They were ably supported by a cast of young actors, all of whom held their own as performers. I must say that I was very pleased when all their characters were resurrected towards the end of the episode, as having a Horror of Fang Rock-style denouement in which only Bill and the Doctor survived would have been too downbeat for me.

Of course, maybe an ending in which nobody but our two protagonists got out alive would have been appropriate. Some critics like to talk about the way in which Doctor Who crashes into different genres due to its not-quite-an-anthology-show format. Knock Knock, despite some superficial science fiction trappings (the insects, whose origin we never got to the bottom of), sat firmly in the horror genre (in fact, as I watched, I found myself thinking of the work of the late, great writer Nigel Kneale, who similarly liked his science fiction with a side-order of scares). The question in my mind, though, is whether this story took things a bit too far? This was the first time that the 10-year-old I watch with was scared to go up to bed afterwards and I have read that the press preview had a 12 certificate, which is not great for a family show (some previous episodes, like The God Complex have also been awarded a 12 rating, so it’s not unheard of.). Some of the content, I thought, was a bit much for younger viewers, such as when characters were sucked into or embedded in the walls and floors of the house or when they were eaten by insects. Oh, dear, I seem to be channelling Mary Whitehouse a bit now…
Another problem I had with Knock Knock was in terms of its plotting. I felt there were a fair few questions left unanswered by Mike Bartlett’s script. How exactly did the Landlord learn to control the alien insects? We know that, as a boy, he noticed them responding to a music box but it seems a bit of a leap that he was, using this information and, presumably, trial and error, able to work out a series of (sonic?) commands that they would obey. Also, why was the frequency of student disappearance every 20 years and why weren’t those disappearances followed up on? And how did the Landlord’s mother suddenly gain the ability to control the alien insects at the end of the episode? Perhaps I wasn’t paying attention and the explanations to all these questions (and some others I had) were in plain sight. If so, feel free to scold your inattentive reviewer in the comments section below…

I’m very aware that I’ve spent most of the review moaning about issues I had with this episode, even though I enjoyed it. Let me end by talking about an aspect of Knock Knock, and of the whole season, that I have no reservations about whatsoever – Nardole. I wasn’t looking forward to seeing Matt Lucas back in Doctor Who. This isn’t because I don’t rate him as an actor. I do. I just didn’t particularly take to the character in The Husbands of River Song (he was better in The Return of Doctor Mysterio but I still wasn’t convinced). That has completely changed. I think he’s worked wonderfully in recent episodes, particularly because he hasn’t been over-used. He reminds me of Romana (as played by Lalla Ward), a character who was prepared to answer the Doctor back and engage in a bit of banter. I’m really looking forward to seeing Nardole join the Doctor and Bill for a full outing next week, which is not something I ever expected to write…
I’m really enjoying this season. Peter Capaldi is getting the characterisation his Doctor deserves, Bill is a great companion, and even Nardole is turning out to be a pleasant surprise… Good times, fellow Who fans. Good times.