Thin Ice (TV story)

 was the third episode of the tenth series of Doctor Who produced by BBC Wales.

Synopsis
The Twelfth Doctor and Bill visit the last great frost fair in 1814, but something sinister is lurking below the frozen Thames.

Plot
The Twelfth Doctor and Bill, having just experienced the events of Smile, dress up in period clothing and begin to explore Regency London. As they leave the TARDIS, they miss an alert message that a large creature is living in the River Thames. As they walk, a street urchin offers them a flyer for the Frost Fair on the Thames, which they attend.

Bill notes that Victorian London is a lot more racially diverse than she remembers from the movies. The Doctor remarks that "history is a whitewash". Whilst enjoying the festivities, Bill notices strange green lights under the ice and follows them; the Doctor reveals he had noticed them too, but let Bill have fun while she could before they get to work.

Elsewhere, a drunken man follows the lights across the ice to an area of thin ice before being sucked under leaving only his drink bottle behind.

The Doctor and Bill are approached by a girl looking for her dog that has gone missing, the girl wanting their help. However, the Doctor deduces that she is trying to con them, catching a boy's arm as he attempts to pickpocket his sonic screwdriver from behind, only for the girl to kick his leg, enabling the pair to flee. The Doctor and Bill give chase across the ice but the boy becomes distracted by the green lights and is sucked under leaving only his outstretched arm, with the sonic screwdriver, protruding through the ice.

Though the Doctor tries, he cannot save him and only manages to retrieve his screwdriver. His relief at having done so and his seeming lack of care towards the boy's death causes Bill to run off and then confront him. She demands to know how many people he's seen die- he doesn't know- and how many people he's killed- he doesn't say. The Doctor tells her that he is 2000 years old and doesn't have the time for the luxury of outrage otherwise more people would die.

The girl, Kitty, takes the Doctor and Bill to meet the rest of the urchin gang- including the girl who handed Bill the flyer. After gaining their trust by giving the children food and the Doctor reading to them, the urchins explain that a man with a tattoo of a ship on his hand pays them to lure people onto the ice by handing out flyers.

Bill and the Doctor put on dive suits and walk out onto the ice. They cannot hear each other with the helmets on and the lights begin to surround Bill. She throws her lantern at the Doctor to gain his attention before she is sucked under the ice. The Doctor jumps through before it reseals and underwater discover a giant sea creature chained at the bottom of the river.

Bill sees the hat belonging to the boy who was sucked under in its mouth before they come back to the surface. The Doctor discovers some of the fish causing the lights and determines that they may be terrestrial. Bill notes that the creature sounded miserable from its imprisonment.

The Doctor gets information from a local fisherman and the pair discover a group of dredgers harvesting the waste from the creature from the Thames. Using the psychic paper under the pretence of conducting an inspection, the Doctor and Bill learn that the waste of the creature is more efficient than coal and can even burn underwater making it a highly valuable resource.

They visit the manor home of the employer Lord Sutcliffe to determine whether he is an alien. The Doctor insists he do the talking as they must charm Sutcliffe and Bill is likely to become angered due to the creature eating the children. Under the guise of "Doctor Disco of the Fairbrook Society" the Doctor meets Sutcliffe who instantly makes sexist, classist but mainly racist, remarks towards Bill calling her a "creature" and to show "respect in the presence of [her] betters". In response, the Doctor punches him in the face, knocking the man down, and determining that Sutcliffe is very clearly human.

Bill and the Doctor are quickly captured by Sutcliffe's co-conspirators with a bruised Sutcliffe revealing the creature has been a family secret for years. He attracts people onto the ice by helping to fund the Frost Fair to be sucked under and provide fuel. He plans to blow up the ice to caisle widespread panic and deaths before the ice thaws and keep the creature a secret. Leaving Bill and the Doctor tied up with the explosives, Sutcliffe prepares to blow the ice up.

Working together, Bill manages to hand the Doctor his sonic screwdriver who uses it to attract the glowing fish to them whilst also cutting through the ropes they're in. Their guard rushes in and the Doctor hands him the sonic causing the fish to become attracted to him and suck him through the ice. The Doctor gives Bill the choice saying he only serves the human race; save the creature but risk it killing the people they'd worked to save or kill it even though it was innocent. Bill chooses to save it.

Bill, with the help of the urchins, manage to convince everyone the ice is melting to get them off the ice causing Sutcliffe to rush his plans and detonate immediately. However, the Doctor had used his dive suit to plant the explosives around the chains of the sea creature releasing it. The creature begins to swim away cracking the ice above it and causing Sutcliffe to fall into the water to his death. The Doctor pulls Bill off of the ice before she falls through and they are drenched by the creature as it swims to freedom without harming anyone.

Later, Bill and the Doctor invite the urchins to Sutcliffe's home to be fed and cared for with the Doctor amending Sutcliffe's Last Will and Testament so that everything passes to Perry, one of the urchins.

Back in the Doctor's office, Nardole, who was just finished making tea is shocked when he notices their period clothing, giving away that they had been time travelling. He reminds the Doctor of his vow whilst Bill is surprised that googling the sea creature from 1814 turned up no results. The Doctor explains that humans tend to overlook the inexplicable and that the Frost Fair involved a lot of day drinking. He shows her the headlines which detail Lord Sutcliffe's death and, despite the contestion of inheritance, Perry was eventually deemed the legitimate heir.

The Doctor and Nardole toss a coin for whether the Doctor keeps his vow and remains on Earth, or Nardole leaves him alone. The Doctor wins and presumably goes off in the TARDIS with Bill whilst Nardole checks the vault. As he goes to leave, knocking comes from inside, Nardole refuses to let the entity inside out before hurrying away looking very worried.

Cast

 * The Doctor - Peter Capaldi
 * Bill - Pearl Mackie
 * Nardole - Matt Lucas
 * Sutcliffe - Nicholas Burns
 * Kitty - Asiatu Koroma
 * Pie-Man - Peter Singh
 * Overseer - Simon Ludders
 * Dowell - Tomi May
 * Spider - Austin Taylor
 * Dot - Ellie Shenker
 * Harriet - Kishaina Thiruselvan
 * Perry - Badger Skelton

Culture

 * The Doctor refers to the whitewashing in history.
 * He mentions Jesus Christ as an example of this.
 * Bill mentions that there were more black people present in Regency London, than shown in movies.
 * A frost fair is being held on the frozen River Thames.
 * The Doctor and Bill encounter an elephant walking past.
 * A map for 19th century London is displayed on the TARDIS console.

Biology

 * Bill refers to the melanin in her skin.

Technology

 * A detonator is seen wired up to explosive barrels.

Food and beverages

 * The Doctor steals fish pies from a con-artist.

Species

 * A giant sea serpent is held chained beneath the Thames. After it breaks free, the icy river cracks, and ends the frost fair tradition.
 * Lure fish were swimming in the River Thames, luring people out on the thin areas of the ice with their green light bulbs and trap them underneath for the serpent to feed on.

Locations

 * The TARDIS lands on the bridge next to New Lime Wharf.

Story notes

 * The read-through for Thin Ice took place on 18 July 2016, and filming on the episode began on 1 August.

Ratings
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Filming locations
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Production errors
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Continuity

 * The Doctor and Bill find themselves on the middle of the frozen River Thames with an elephant crossing their path. (TV: Smile)
 * The Doctor previously visited the 1814 Frost Fair with River Song. They brought Stevie Wonder with them to perform. (TV: A Good Man Goes to War)
 * He mentions having been here before, "a few times". (AUDIO: Frostfire, PROSE: The Frozen, TV: A Good Man Goes to War, Silhouette)
 * According to the short story The Frozen, in February 1814, the Hyban Masoon froze the Thames on arrival.
 * In Regency London, Bills voices her fear that she will be slaved due to the colour of her skin. Martha Jones voiced the same concern when she visited London of 1599 with the Tenth Doctor. (TV: The Shakespeare Code)
 * Bill is concerned about the butterfly effect, also exactly like Martha in her first visit to London's past. (TV: The Shakespeare Code)
 * Bill asks about physical side effects of time travel. (TV: The End of the World, Doomsday, The Sound of Drums et al.)
 * The Doctor reminds Bill of her recent experience with death when they visited a garden full of dead people. He confirms this was only a few hours before this episode. (TV: Smile)
 * The Doctor once again notes humanity's habit of overlooking and forgetting the bizarre. (TV: Remembrance of the Daleks, In the Forest of the Night) Charlie Smith noted the same after the Shadow Kin came close to invading Earth through Coal Hill School. (TV: The Coach with the Dragon Tattoo)
 * Nardole reminds the Doctor of his oath. (TV: The Pilot, Smile)
 * Nardole mentions being reassembled. (TV: The Husbands of River Song, The Return of Doctor Mysterio)
 * The Doctor again mentions how you don't steer the TARDIS; you reason with it. (TV: Smile)
 * The Doctor once more states that he's 2000 years old. (TV: Deep Breath, Smile)
 * The Doctor is asked how many people he has seen die. (TV: Journey's End) He remarks on how he has lost count. (TV: The Day of the Doctor)
 * The Doctor punches someone in the face out of anger and defence of his companion. (TV: Hell Bent)
 * Sutcliffe refers to the Doctor as "Doctor Disco". (TV: The Zygon Invasion)

DVD releases
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Blu-ray releases
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Digital releases
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