Loved the episode! Creepy as hell. The reverse psychology of the landlord being the son instead of the father was interesting. The plot of the son not being able to let go of his mom is truly emotional.

The actors were once again amazing, special mention to David Suchet!

For me, the highlight of this episode was David Suchet’s performance. His character had such presence, switching between nice, ruthless and vulnerable in the blink of an eye. I loved that he was a boy that had never grown up and that he’d spent his life protecting his Mum. Yes, he did terrible things, but from that perspective, I left the episode feeling a lot of sympathy for him and I was glad that both him and his mother had finally found peace. The way that David was able to portray that childlike aspect of the character at the end was beautifully played and I’m only sorry we won’t get to see more of him.

As a Revived Era fan, I liked that the 12th Doctor listed Harriet Jones, former Prime Minister (Yes, I know who she was) amongst the list of possible Prime Ministers. I really like nods like that back to the past and it was great to see her remembered.

Bill haphazardly ending up calling The Doctor “Grandfather” was a strange one for me. Obviously, it makes Doctor Who fans immmediately think of Susan, as that was how she referred to him, and despite not being a Classic Era fan, I felt strangely uncomfortable about Bill calling him that. In a way, I’m surprised it didn’t seem to mean anything to the Doctor, particularly because he had a picture of Susan on his desk, suggesting his incarnation has been thinking about her and River (IE: family).

The monsters in this episode weren’t the focus and I think that was intentional. They were secondary to the story of the mother and son and that was great, but it means that there’s not much to say about them and it’s fair to say that I didn’t find them particularly scary, but then I don’t think they were meant to. Whilst watching, they actually reminded me quite a lot of the gruesome scarabs from The Mummy films.

Once again, the episode ended by returning to The Vault and its captive playing the piano. I feel that they’re building the mystery well about who or what is inside and I want to know more and more after each episode, only enhanced by the seemingly cultured nature of the captive. I’m not sure it’s as simple as The Master or The Mistress though, but perhaps it is.

The reason I wonder is because although The Doctor peaked the captive’s interest by mentioning walls eating people, that could be because the captive is sadistic like The Master and The Mistress or it could simply be because it makes the story juicier and more interesting for the person or the thing inside.

Once again, the main thing I will take away from this episode is David Suchet’s performance.

Other than David Suchet and Peter C’s performance. this was a return to Steven Moffat humanisation of Doctor Who dreariness! A promising start but what a pathetic finish. As always with Moffat, a good story turned into drivel! The first major low point in the season!

I loved this episode it gave me lovely flashbacks in my opinion the mother/son bond made me think back to Jamie and Nancy that protection of blood throughout life. A little Harriet Jones mention * The alien reaction of mother was amazing the look and the way she moved. David Sydney amazing so creep amazing role. I want to know what is in that vault

Great nuanced performance by David Suchet, both menacing and sympathetic.

Liked the haunted house/gothic horror movie feel to the whole thing. Quite atmospheric.

I loved the chemistry between Bill and the Doctor in this episode. I think it saved the episode. I didn’t find it scary compared to other episodes but thought it showed what life is like with the Doctor is in your life. Suchet was good as the creepy landlord. Did anyone else think it’s Missy in the vault??

David Suchet was absolutely brilliant as the landlord and the plot twist that the wooden woman in the tower was his mother rather than his daughter was amazing, but the love he had for her and what he did to protect her was heart wrenching, loved the creepy house and the creaky floors and walls was perfect, I would definitely stay there as I love creepy things. The acting all round was fantastic and a big thumbs up for this episode. Well done! xxx

Firstly I loved David Suchet. A great performance making you feel sympathetic for him by the end. Needless to say Peter was brilliant as usual. Not entirely comfortable with Pearl yet but replacing Clara was always going to be difficult. The sets and effects were excellent. The plot though not startlingly original was decent. Overall an enjoyable episode but not a classic.

@Sam freke “replacing Clara was always going to be difficult” – Really? Replacing an obnoxious bullying unpleasant person with a person of character and adventure is difficult? Nah! Bill has wiped the floor with Amy and Amy 2 (also called Clara) and is much more likeable!

Each season of Doctor Who I feel is required to have that one stand out scary episode, Season 3 had Blink, Season 7 had Hide,Season 8 had Listen and now Season 10 has Knock Knock which can join the other mentioned episodes as one of the best scary episodes in Who-History!

A very creepy, suspenseful episode with a very emotional yet unnerving twist always works well. Has Great ideas like Space Insects and the house being almost alive and eating people and I agree with what everyone else is saying David Suchet gave a great performance as unnerving mysterious presence to begin with but when the twist is revealed he did such a great job of showing this twisted old man as a scared kid who just wants to save his mother.

While I think character development with Bill and the Doctor took a back seat in this episode that’s fine because that way we had more focus on the suspense and mystery so that worked well and the ending with the vault is really intriguing and I like how so far in the series they’re giving us just the right amount of details to keep us very intrigued.

For a first time Doctor Who writer Mike Bartlett did a great job and really hope he returns. It’s almost a shame really that this episode was written to fit into BBC’s family friendly area, I bet with more screen time and higher age rating/ maturity we could have gotten a really scary episode and yet it’s memorable all the same!

Pretty Good episode. A interesting take of the haunted house idea.

I might be the only one who thinks this, but I think the ending really ruins this episode. It’s almost American in nature (and while I live in the states, in no way do I mean this as a compliment) — it’s just too childish for me.

Certainly better than some of the other episodes this season though.