Knock Knock (TV story)

 was the fourth episode of the tenth series of Doctor Who produced by BBC Wales. This was the first Doctor Who story to be made available with a binaural 360 soundscape, released on iPlayer.

The episode expands the Doctor and Bill's relationship briefly when he tells her about the Time Lords, the alien race he belongs to and quickly mentions regeneration to her, but doesn't explain what regeneration actually is to her.

It also makes a reference back to the Doctor's granddaughter Susan Foreman, as Bill passes the Doctor off as her grandfather and refers to him as such. She has also told her friends about him; although, the Doctor doesn't seem to have much of a problem with it.

The Vault is also implied to not just have the mass it appears to have, instead being dimensionally transcendental. The prisoner inside is heard playing a piano the Doctor gave them.

Synopsis
Bill and her friends rent an old house to live in, but the floorboards and the walls are creaking, and there's a creepy Landlord lurking around. Can the Twelfth Doctor save the day as creatures come crawling out of the wood?

Plot
Bill opens her door to find her friends outside. They head to the rel-estate office to find a place to rent together. However, the agent that helps them keeps finding places that are less than satisfactory. They head out to try somewhere else, only to be met by an elderly man named John, who offers to help them find a place. He shows them to an old house, which they assume will cost them a lot to rent; he assures them that rent will be cheap, telling them the tower is off limits.

Everyone explores the house, finding the rooms acceptable. Pavel asks to move that night as his host parents are kicking him out. The Landlord lets him, getting everyone to sign a contract. That night, Pavel plays music in his room, only to be surprised by something horrifying.

The next day, Bill is stacking up her belongings in boxes in her room. After everything is in on corner, she looks at her phone and counts down. The TARDIS appears over the boxes, which end up inside. The Doctor opens the door, surprised, thinking Bill had a lot more belongings than that.

Bill enters the TARDIS, suggesting that the Doctor offer his TARDIS as a moving service or package delivery. The Doctor is offended at the idea, stating that he's a Time Lord. Bill laughs at it, noting how posh it sounds. The Doctor notes that's why he ran away from his people. Bill asks if Time Lord wear robes and hats. The Doctor tells her the robes are true, but Time Lords tend to wear big collars instead of hats.

When asked if he needs the address to find the house, the Doctor scoffs; however, he then relents and tells Bill to type it in so the TARDIS can land there. She asks him where he lives, telling the Doctor that everyone needs sleep. The Doctor tells her that Time Lords don't need sleep, except after big meals and regenerations. Bill is confused by his words, but the Doctor tells her that just knowing he's a Time Lord is enough for now.

The TARDIS lands outside of the house, with the Doctor confused as to how the rent can be so cheap. Bill thanks the Doctor for helping her, telling him he can leave once her boxes are out of the TARDIS. However, the Doctor has noticed something off and decides to help Bill move her stuff.

Inside, the Doctor is greeted by Shireen, who knows about him. Bill passes the Doctor off as her grandfather, despite his protests. Felicity, Paul and Harry join them, having also been told who the Doctor is. Bill tries to get rid of the Doctor, who seems to relent and leaves the house.

Cast

 * The Doctor - Peter Capaldi
 * Bill - Pearl Mackie
 * Nardole - Matt Lucas
 * The Landlord - David Suchet
 * Eliza - Mariah Gale
 * Shireen - Mandeep Dhillon
 * Felicity - Alice Hewkin
 * Paul - Ben Presley
 * Harry - Colin Ryan
 * Pavel - Bart Suakvek
 * Estate Agent - Sam Benjamin
 * Young Landlord - Tate Pitchie-Cooper

Culture

 * Bill makes reference to Indiana Jones.
 * Shireen says "I'm a celebrity, get me out of here", a reference to the reality TV series. She also refers to the building as a "freaky Scooby Doo house".
 * Paul says that a freshers' party is being held in the park.
 * Fireworks are used at the party.

Music

 * The figure behind the Vault can play the piano.
 * Pavel has a vinyl record, DVD players and speakers.
 * Bill has a whole playlist on Spotify with Little Mix on her phone. The playlist includes the song Black Magic.
 * One of the tenants from 1977 owned the David Bowie album Heroes.
 * Pavel has Bach: Sonata #1 by Itzhak Perlman playing in G Minor for Solo Violin, BWV 1001 - 1. Adagio.
 * The figure behind the Vault plays Für Elise by Beethoven and Pop Goes The Weasel, a famous nursery rhyme, on a piano.
 * The song heard at the start when Bill and her friends are looking for a house is Weird People by Little Mix.

Locations

 * When Felicity bemoans the lack of phone reception, Shireen says she needed a landline and Felicity jokingly asks "What is this, Scotland?".
 * A house on Mill Lane, Bristol, is shown on the estate agent's computer.
 * The park is the location of a freshers' party.
 * Shireen has once been to Morocco.

Businesses

 * A shop named The Fabric Mill is seen.
 * A cement factory can be found next to one of the houses that the students check out.

Technology

 * The house has no washing machines.
 * The plugs can't take the students' phones.
 * The house has an old-fashioned television set.
 * The hob is from the 30s.
 * Pavel plays a vinyl record using a USB turntable.
 * The Doctor uses the sonic screwdriver as a light source.
 * Eliza has a music box.
 * There's a typewriter in the basement.

Science

 * The Doctor finds an oil burning heater.

Species

 * 11 Cardinal Road has skulls from gazelles hanging on the walls.
 * Paul and Shireen jokes to Felicity that the house possibly has a "doll, that's come to life" or a "massive, freaky spider", to which Bill says it's probably just a mouse, and Felicity indirectly says she has a fear of mice.
 * Bill asks if there's a cat in the house. The Landlord denies this.
 * Time Lords need to sleep after regeneration.
 * At first, the Doctor suggests that the walls could be infested with wood nymphs or tree spirits.
 * Upon discovering the Dryads the Doctor says he expected a gaseous creature or a microscopic one.
 * The Doctor calls the woodlice Dryads, though he later reverts to just calling them lice.
 * The bass player in Quincy Jones' band turned out to be a Klarj Neon Death Voc-Bot.
 * Shireen thinks the Dryads are cockroaches.
 * The Doctor mentions flies.

Foods and beverages

 * The house has a picture of a bowl of pears.
 * There's a book on Farmhouse Cooking in the kitchen.
 * The students eat Chinese. The Doctor loves Chinese.
 * The Doctor (noisily) eats a krupuk.
 * The Doctor brought Mexican food for himself and the prisoner in the Vault.

People

 * Bill has a teddy bear.
 * Harry's grandfather and his boyfriend once got arrested for trying to steal a bit of the Great Wall of China.
 * Bill hangs up a photo of her mum.
 * Asking the Landlord who is the Prime Minister, the Doctor lists Margaret Thatcher, Harriet Jones, Harold Wilson and Anthony Eden as candidates.
 * The Landlord has a tuning fork.
 * The Doctor calls Harry "Simon" and Felicity "Florence".
 * The Doctor once sat in on a recording session for Quincy Jones when the bass player (who couldn't play anyway) was revealed to be a Klarj Neon Death Voc-Bot.
 * Felicity is Musophobic and Claustrophobic.
 * Felicity tried to call the police.
 * Shireen wanted to call an ambulance.
 * A tenancy agreement from 2 September 1997 was signed by Jake Christie, Annie Wren, Jonathan Frost, Sarah Tiller, Mark Hopethorne and Carl Richards. There is a further agreement from April and signed in May 1977 and one from 1957.

Organisations

 * Bill and her friends go to Redcliffe Lettings to find a new house to live in.
 * Redcliffe Lettings' phone number is 01174 960313.

The Doctor

 * The Doctor offhandedly mentions regeneration to Bill; he avoids elaborating on it.
 * The Doctor still can't tell people's ages.
 * He shares stories with the Vault's prisoner, only if their gruesome enough.

TARDIS

 * Bill suggests the Doctor make the TARDIS a removal service.

Story notes

 * The read-through for Knock Knock took place on 18 July 2016, and filming took place in August.
 * David Suchet said in The Fan Show: The Aftershow that he used a real life experience of being covered in woodlice for the scene where the Dryads come crawling all over the Landlord.
 * In an interview for Doctor Who Magazine #512, writer Mike Bartlett indicated that Harry was intended to be the grandson of Fourth Doctor companion Harry Sullivan, but the reference was cut. A possible remnant of this has Harry recognising the Doctor's name and calling him a "legend", despite the episode establishing that Bill is not yet closely acquainted with her new flatmates; another is the fact that Harry is partnered up with the Doctor for part of the episode. There is also a dialogue reference made to Harry's grandfather and his boyfriend stealing a piece of the Great Wall of China, however it is not clear whether this refers to Harry Sullivan or another grandparent.
 * "Weird People" by Little Mix is playing extra-diegetically in the scenes where Bill and her friends are looking for a new house.
 * Shireen refers to 11 Cardinal Road as "a freaky Scooby Doo house". The episode was partly filmed on location on the same property used for Wester Drumlins in TV: Blink - in which a character also referred to the place as "Scooby Doo's House".
 * Not really noticed by everyone, but everything the Bill and her friends brought to that house either ended up buried or destroyed when it fell apart.

Ratings

 * 4.32m (UK overnight figures)
 * 5.73m (UK final)

Filming locations

 * Fields Park Road, Newport, South Wales

Production errors
to be added

Continuity

 * The Doctor mentions Prime Minister Harriet Jones, who ascended after aiding his ninth incarnation in defeating the Slitheen. (TV: Aliens of London/World War Three) His tenth incarnation, however, would set in motion her deposition after she ordered the destruction of the retreating Sycorax. (TV: The Christmas Invasion) She would help save the world one final time against the Daleks. (TV: The Stolen Earth)
 * The TARDIS materialises around Bill's possessions. It had done so previously around passengers. (TV: The Parting of the Ways, Blink, The Runaway Bride, Dinosaurs on a Spaceship, Hell Bent)
 * The Doctor mentions that he ran away from his people. (TV: The Name of the Doctor)
 * The Doctor says he loves Chinese. (TV: The Power of Three)
 * Bill says there are bits of her life that the Doctor is not in. Amy Pond and Rory Williams used to have a double-life, (TV: The Power of Three) and so did Clara Oswald. (TV: The Day of the Doctor)
 * When Bill says they should get the Doctor, Shireen asks if he's gonna give a lecture. (TV: The Pilot)
 * The Doctor remarks on the Time Lords' dress sense, having done so earlier in his life. (TV: Time Crash, Journey to the Centre of the TARDIS, Nightmare in Silver, Hell Bent) He makes note of the high collars (as seen in TV: The Deadly Assassin, et al).
 * The Doctor reveals he's a Time Lord. (TV: The War Games et al., Doctor Who, The End of the World et al.) Upon learning this, Bill scoffs at the Doctor being part of the aristocracy (TV: The Caretaker).
 * Regeneration is mentioned. (TV: The Tenth Planet/The Power of the Daleks, The War Games, Planet of the Spiders/Robot, Logopolis/Castrovalva, Destiny of the Daleks, The Caves of Androzani, Time and the Rani, Doctor Who, The Night of the Doctor, The Day of the Doctor, The Parting of the Ways, Utopia, The Stolen Earth/Journey's End, The End of Time, Day of the Moon, Let's Kill Hitler, The Time of the Doctor, Hell Bent) However, the Doctor glosses over the topic, similar to how his tenth incarnation did such with Martha Jones in regards to his race. (TV: Gridlock)
 * The Doctor had previously faced creatures who absorbed people into walls. (TV: Flatline)
 * Bill introduces the Doctor as her grandfather. The Doctor once travelled with his granddaughter Susan Foreman, who called him grandfather. (TV: An Unearthly Child - The Dalek Invasion of Earth, The Five Doctors)
 * The Doctor takes offence at being described as Bill's grandfather, suggesting father be more accurate given his appearance. (TV: The Caretaker)
 * Bill's sexuality is mentioned as she informs Paul, after he makes romantic overtures, that he isn't her type and she prefers girls. (TV: The Pilot)
 * Bill puts a picture of her mother, which was taken by the Doctor, on the wall. (TV: The Pilot)
 * One of the flat mates theorise dolls could be creeping around upstairs. The Doctor encountered a house of dolls in his eleventh incarnation. (TV: Night Terrors)
 * The Doctor uses the sonic screwdriver as a light source. (TV: Thin Ice)
 * The Doctor has met people made of wood before. (TV: The End of the World, The Doctor, the Widow and the Wardrobe)
 * The Vault is tended to by Nardole once more, the Doctor revealing a piano is inside. (TV: The Pilot, Thin Ice)
 * In an attempt to convince herself that there's nothing strange about the house, Bill remarks that "There's no living puddles or weird robots, big fish..." (TV: The Pilot, Smile, Thin Ice)
 * The Doctor claims sleep is for tortoises, (TV: The Talons of Weng-Chiang) as he doesn't sleep much himself, (TV: Good Night) usually only after regeneration (TV: Spearhead from Space, Robot, Castrovalva, Time and the Rani, The Christmas Invasion, Deep Breath) or after a big lunch. (TV: The Two Doctors)
 * The Doctor refuses to "high-five" Harry. (TV: Time Crash, Under the Lake)
 * Nardole says the prisoner has gotten a little restive lately. (TV: Thin Ice)

DVD releases
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Blu-ray releases
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Digital releases
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