The fourth episode of the tenth series of Doctor Who has just aired, so it’s time to review it! This week’s episode of Doctor Who was entitled Knock Knock and was written by Mark Bartlett and directed by Bill Anderson. In this episode, Bill (Pearl Mackie) and several of her friends move into a creepy old house owned by a mysterious Landlord (David Suchet). As the house starts making noises, Bill’s friends begin to disappear. What is causing these noises and disappearances, and can Bill and the Doctor put a stop to it before it’s too late? As always, this review will have spoilers for the episode – so, stop reading now if you haven’t seen it! 

Unlike the previous three episodes, Knock Knock returns to a more typical Doctor Who formula: weird things happen, the Doctor and the companion get caught in the middle of it, and they spend the rest of the episode solving the mystery. For much of the episode, Bill and the Doctor aren’t onscreen together. This is actually a good thing. I know for the past few weeks I’ve been praising the show for focusing so much on the dynamic between Bill and the Doctor, but it’s time to see if Bill can stand on her own as a companion without the Doctor always being onscreen with her. Turns out, Bill is an even more amazing character when she’s not around the Doctor! Everything great about Bill that’s been observed since the season began is very much still on display in this episode. It’s great to see her being written with such consistency. I also dug her reluctance to let the Doctor interfere with the goings on in the house; she wants him to be separate from some parts of her life, and I’m really digging this trend of having the companions have separate lives outside of their lives with the Doctor. It gives them another dimension and lets them have characteristics of their own instead of always having their characters be tied up with the Doctor. It gives them their own sense of urgency; they choose what they’re doing and when they do it. I dig it.

So, the version of Knock Knock that I watched was the binaural version on BBC iPlayer, and I definitely think this version is probably the version to watch. Is a special binaural mix version of an episode a gimmick? Yeah, definitely. Did it work beautifully and serve the story, and the episode, well? Absolutely. Knock Knock is, at its heart, a horror movie. Condensed into forty-five minutes, obviously. And it has, as every good horror movie must, an incredibly spooky atmosphere. The sound design of this episode was integral to creating the atmosphere needed to make it work. Being able to hear the various knocks coming from all sides of you genuinely adds a lot to the experience. You can understand why the characters are reacting the way they are. There’s something about a loud knock coming from right behind your left ear that makes you jump, and it’s effective to then hear another knock coming from in front of your right ear. It just really makes the atmosphere work and gets you in that zone of heightened tension that’s so conducive to being scared by horror movies.

As for the plot, it’s not the strongest plot ever, but it’s not bad. The episode’s not gonna win any awards for superb storytelling, but it’s a fine episode. Some reviews have said that the third-act reveal makes the episode as a whole less scary, and I disagree. I like that the Landlord was given a motive for what he was doing, but I still found the idea of what was happening to be a frightening one, regardless of the motivation behind it. I don’t want to be trapped in an old house, with no way out, surrounded by loud knocking that I can’t identify, and then be potentially absorbed into the wood of the house. That’s scary. Period.

Once again, Bill Anderson does a fine job directing, though the shining stars really are the people behind the sound mix. I loved how cheesy the visual effects looked in the episode. Several times, lightning flashes behind the house, and it looks so cheap, but it actually adds to the atmosphere by making it feel like an old horror movie. Somehow the episode benefits from having mediocre visual effects; I was pleasantly surprised by this. All the guest actors do fine jobs; none of them really stand out, but they were all good. Peter isn’t given a whole lot to do in the episode, which is fine. It’s nice seeing him try to cope with having to give Bill space. It was a nice dynamic to add. Pearl Mackie continues to shine as Bill, still giving her lots of dimension and pathos. Pearl is just a superb actress. David Suchet does a lovely job as the Landlord, giving him just the right amount of creepiness without ever going over the top and then embedding him with sympathy when the episode later calls for it.

Again, Nardole only appears at the end of the episode, and his appearance is uneventful. But, what happens once Nardole leaves the scene is interesting. The Doctor starts talking to whatever/whoever is in the Vault (under St. Luke’s) that the Doctor’s been guarding. Music comes from inside the Vault, and the Doctor asks what’s inside if it would like dinner – he’s brought Mexican food – and asks if it would like to hear a story. At first, whatever’s inside the Vault doesn’t seem interested, but as the Doctor explains the story and mentions that teenagers were being eaten and killed, the thing inside the Vault got a whole lot more interested. And that’s where the episode ends. In the latest issue of Doctor Who Magazine, Moffat revealed that we’ll find out what’s in the vault in Episode 6. But this little tease at the end of the episode has really gotten me interested, excited, and frustrated. I wanna know what’s in the Vault! (I have my suspicions, but the scene gave me some doubts about my guess – originally I thought the John Simm Master was in the vault (since it’s been confirmed that he’s returning this season, it would be interesting to have the Doctor be protecting/imprisoning this version of the Master until he regenerates into Missy), but then in this episode, the Doctor kind of spoke to the Vault like it was a child, making me think that maybe Susan’s in it?) So, I dunno what’s in the Vault, but I wanna find out!

All in all, Knock Knock was another good episode of Doctor Who. This season’s been full of good episodes so far, so I hope this trend continues!

I give the episode 4 out of 5 stars!

Doctor Who continues next week with Oxygen, airing at 7:15pm BST on BBC One and 9pm EDT on BBC America.