History Recap / DoctorWhoS36E4KnockKnock

* ShoutOut: The ''Magazine/RadioTimes'' poster alludes to David Suchet starring in ''Series/{{Poirot}}'' via its art deco style and the man's costume.

* SupernaturallyYoungParent: The landlord is initially thought to be Eliza's father, but is in reality her son, who has been keeping her youthful and immortal artificially through the use of the dryads. He passes himself off as Eliza's father in order to explain away the fact that he looks decades older than his mother.

* TranquilFury: When The Doctor first confronts the Landlord over the disappearance of the roommates he gives an [[TheUnsmile unsmile]] as he asks where they are.

Written by Mike Bartlett.

The one with the monster house... [[ShapedLikeItself made of monsters.]][[note]]Not to be confused with ''WesternAnimation/MonsterHouse'', but the premise is very much the same- right down to the creepy old man.[[/note]]

* AdultFear: Your child is looking for a house of their own but can't find anything in their budget and then a seemingly kind stranger provides them with an offer that is too good to be true. They quickly sign a contract and just as quickly come to regret it. Bill is direct with this one and tries to reassure herself that she is not on a scary adventure, just moving into a new house with five strangers.

[[caption-width-right:350:[[labelnote:Click here to see the RadioTimes magazine poster for this episode:]] https://static.tvtropes.org/pmwiki/pub/images/knockknock.jpg Who's there?]][[/labelnote]]

* ShoutOut: The ''RadioTimes'' poster alludes to David Suchet starring in ''Series/{{Poirot}}'' via its art deco style and the man's costume.

* ForbiddenFruit: The Landlord tells the tenants that they're not to enter the tower, which they of course try to anyway.

* NoodleIncident: The Doctor mentions that he once met musician Quincy Jones... and that Jones' bassist during that meeting turned out to be an alien in human disguise. He doesn't seem to elaborate beyond that.

* PowerUpgradingDeformation: Eliza keeps living, but was turned into wood by the Dryads.

* RedemptionRejection: After discovering the truth of what her son did and seeing the world outside for the first time in decades, Eliza prepares to have the Dryads devour her, and tells the Landlord to make the most of his remaining years. The Landlord refuses, and tries to make them turn on the Doctor and Bill, in turn causing Eliza to have them devour her ''and'' her son.

* RelativelyFlimsyExcuse: Bill claims to her housemates that the Doctor is her grandfather. He prefers "father" because he is not nearly old enough to be grandfather, ''obviously''.

* SupernaturallyYoungParent: The landlord is initially thought to be Eliza's father, but is in reality her son, who has been keeping her youthful and immortal artificially through the use of the termites. He passes himself off as Eliza's father in order to explain away the fact that he looks decades older than his mother.

Also, the one with [[Creator/DavidSuchet Poirot]]

The Doctor uses the TARDIS to help her move her belongings to the beautiful old house where she and her friends will each have a space of their own for dirt-cheap rent. But standing outside the house, listening to the wind blowing through the trees...he hears something that he realizes is ''not'' the wind.

* ContrivedCoincidence: The Landlord only rents out rooms once in every 20 years, yet in city a millions one of the new tenants just happens to be the Doctor's current companion.

[[Series/{{Poirot}} David Suchet]] guest stars as the Landlord. Official trailer [[https://www.youtube.com/watch?v=pN3ppXuAqag here.]]

[[caption-width-right:350:''"Are you looking for somewhere to live?"''[[note]]From left to right: Shireen, Paul, the Landlord, Bill and Harry.[[/note]]]]

* TheFogOfAges: The insects have been keeping Eliza alive, but they're not so good at preserving memories, so she doesn't even remember her actual relation to the Landlord. He takes advantage of this to pass himself off as her father, when he's actually [[spoiler:her son]].

* SupernaturallyYoungParent: The landlord is initially thought to be Eliza's father, but is in reality [[spoiler:her son]], who has been keeping her youthful and immortal artificially through the use of the termites. [[spoiler:He passes himself off as Eliza's father in order to explain away the fact that he looks decades older than his mother.]]

* TheFogOfAges: The insects have been keeping Eliza alive, but they're not so good at preserving memories, so she doesn't even remember her actual relation to the Landlord.

* PoweredByAForsakenChild: For Eliza to live the Dryads need to eat people.

** The Doctor mentions regeneration to Bill, but doesn't explain what it is.