Knock Knock

"Knock Knock" is the fourth episode of the tenth series of the British science fiction television series Doctor Who. It was written by Mike Bartlett and was broadcast on 6 May 2017 on BBC One. "Knock Knock" received mixed to positive reviews from critics, receiving criticism regarding the strength of the writing, but praise on the quality of the performances in the story, particularly Suchet's.

Bill Potts (Pearl Mackie) and her friends rent a house to live in after a recommendation from its landlord, played by guest star David Suchet, but the Doctor (Peter Capaldi) notices something wrong with the house when the floor and the walls creak and creatures come crawling out of the wood.