10.4. Knock Knock

Series 10 - 2017

Writer: Mike Bartlett
Produced by: Nikki Wilson
Director: Bill Anderson
Music: Murray Gold


Bill, with other students from the University, is looking for a house to share. The estate agent shows them numerous properties that are not suitable. Some are too small, are next to a noisy factory. They leave the estate agents without finding suitable accommodation. Outside they are met by a man who has a house they can rent. When the visit the house it is large, with a large tower that the Landlord says is not safe.

Inside the decor is old fashioned - with wood panelled walls, but the rooms are huge and there are more than enough for the six students along with extras such as audio equipment. Bill questions why the rent is so cheap. Pavel is eager to move in quickly as the halls of residence are kicking him out that day. The Landlord produces a contract and all six students sign. Pavel is the first to move in, with his audio equipment. And he is the first to disappear.

Bill has a unique way of moving her stuff into the house. She stacks it neatly and moments later the TARDIS materialises around it. Rather than alarm the other students Bill asks the Doctor to  materialise outside the house grounds and he helps Bill to carry her stuff inside. He's curious about the house, and how six students could afford to rent such a large house. Inside the house Bill introduces the Doctor has her grandfather.

Later that night, after moving in, the five students (who think Pavel is still upstairs in his room) sit down to eat and chat. Being an old house some creaking is expected, but when they hear noises Bill offers to go and check. The others stand behind her as she opens a cupboard - and finds the Doctor inside. He has been checking out the house - so presumably it is him that has been making all the strange noises they have been hearing.

When the go back to the room they were in the find the Landlord there, checking to see if everything is all right. They mention some faults they have found, such as dodgy wiring, no landline or broadband, and no mobile reception. But when Harry mentions getting in to the tower the Landlord again tells them the tower is out of bounds, and their agreement specifically forbids them from going into it. The Landlord seems harmless, even when he uses a tuning fork to check the walls. But he is unable to answer a siple question from the Doctor: Who is the Prime Minister.

The Landlord leaves, and the students start to go to their rooms. The Doctor stays downstairs. As Paul goes to bed Bill and Shireen hear screams from his room. They hear knocking and thinks its Paul signalling he's okay - until they hear more knocking and shutters start to close. Downstairs the Doctor, Felicity, and Harry, find the outside door has been sealed shut, and that the shutters on the windows have all closed.

Felicity is claustrophobic. As shutters keep closing she jumps out a window. Outside she can see the shutters closing on the windows. She tries to call the police, but as she is doing so she backs into a tree. Inside the Doctor and Harry and hear Felicity scream, but cannot open the shutters to get to her.

Upstairs Bill and Shireen find Pavel embedded in a wall. Bill thinks it may have been his music that caused him to become trapped in a wall. Pavel had been playing a record that had finished, but the turntable was still spinning.  When the Landlord appears, and turns off the record player, Pavel is released and disappears fully into the wall. Bill and Shireen run from the Landlord to the end of the corridor that should be the entrance to the tower. All there is is a bookcase. Bill tugs at the books and finds the switch that the bookcase swing open.

Downstairs in the kitchen the Doctor, after hearning noises, thinks there may be something living in the wood. Tapping at a door he gets a creature resembling a large louse to come out. The Doctor is fascinated by it and tries to chase it. Behind him many more appear covering a door. The Doctor leads Harry into the cupboards he was found in earlier. Only it's not a cupboard - it's a lift. Down in the basement the Doctor and Harry find boxes full of possessions, photographs, and contracts, from people who have previously rented the house. On of the photographs shows a number of the lice - or Dryands (the Doctor's name) for them. They also find the Landlord, and the Doctor asks about the other people who have been in the house. When the Landlord says they are still in the house the Doctor realises he means literally - they are in the wood.

The Landlord tells the Doctor that his daugher was dying, until the creatures saved her. Harry tries to run from the Landlord, and is covered in Dryads before disappearing into the wood of the stairs.

In the tower Bill and Shireen find a lit room - and a girl apparently made of wood. A Dryad leaves the girl's mouth, and Shireen steps on it. As she does more Dryads emerge from the floor, and she suffers the same treatment as Harry. As she disappears the girl becomes more rejuvanated. Moments later the Doctor and the Landlord arrive. The Landlord goes over to his daughter - Eliza - and tells her the Doctor may be able to help her.

The Doctor tries to piece together what happened. He guesses that Eliza was in her room ill. The Landlord found the strange Dryads outside and brought them up to show Eliza. They would have been dormant until Eliza's music box awoke them. It's Bill that corrects the Doctor, saying a man would not bring strange insects upstairs. The Doctor realises his mistake. THe Landlord is not the father of Eliza - he's the son. The Landlord realised that Dryads would keep his mum alive if he protected, and fed, them.

The Doctor tells Eliza that the Landlord has kept her for inside for so long she had missed what was happening outside. When Eliza realises that she, as the parent, is in control of the Dryads she takes her son and absorbs him. She releases Bill's friends before destroying herself, the Dryads, and the house.

Regular Cast

  • Nardole: Matt Lucas
  • Bill Potts: Pearl Mackie

Guest Cast

  • Landlord: David Suchet
  • Eliza: Mariah Gale
  • Shireen: Mandeep Dhillon
  • Harry: Colin Ryan
  • Paul: Ben Presley
  • Felicity: Alice Hewkin
  • Pavel: Bart Suavek
  • Estate Agent: Sam Benjamin
  • Young Landlord: Tate Pitchie-Cooper

Original broadcast on the BBC

Channel Title Date Viewers Rating
BBC 1 (HD) 4. Knock Knock Saturday, May 6, 2017 7:20 PM - 8:05 PM 5.73M

Click here to show repeat broadcasts on the BBC


Missing from the final transmission was the fact that the other grandfather of Harry was in fact a former companion of the Doctor - Harry Sullivan.