Thin Ice (TV story)

 was the third episode of the tenth series of Doctor Who produced by BBC Wales. The events of this story follow on directly from Smile, with the TARDIS arriving in London just moments after the Doctor and Bill leave the planet Gliese 581 D.

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 the previous episode, 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 Regency 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, Spider, 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 screw driver. 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 the food the Doctor stole and 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 even calling her a "creature" and demanding she show "respect in the presence of [her] betters". In response, the Doctor punches him in the face, knocking the man down, 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 cause 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 up the ice.

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, after an emotional consideration, chooses to save it.

Knowing people will be harmed, the Doctor tells Bill to save the people on the ice which she does with the help of the urchins, managing 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 instead, using his sonic to reloop the wires, 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 though they are drenched by the creature as it swims to freedom without harming anyone, pleasing Bill as it is no longer in despair.

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

They soon depart back to St Luke's University, where Nardole, who had just finished making tea, walks into the Doctor's office and 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 soon toss a coin to decide whether the Doctor keeps his vow and remains on Earth, or Nardole leaves him alone. Using a trick he learned from the con artist, 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.
 * Bill mentioned that there were more black people present than shown in movies.
 * A frost fair is being held at the frozen River Thames.
 * The Doctor and Bill encounter an elephant walking past.
 * The frost fair has many activities and performances, notably wrestling, sword swallowing, skittles, cartwheel performers, magicians, ring toss, M. G. Clark Printing Co., souvenir shops, book shops, pubs, The Nelson Arms, The City of Moscow and "try your luck" stalls.
 * A map for 19th century London is displayed on the TARDIS scanner.
 * The Doctor reads Struwwelpeter out loud for the street urchins.
 * The Doctor shows Bill the British Newspaper Archives when trying to find information about the frost fair-incident.

Biology

 * Bill refers to the melanin in her skin.

Technology

 * Spider steals the Doctor's sonic screwdriver.
 * A detonator is wired up to explosive barrels.
 * The sonic screwdriver works underwater.

Science

 * Bill thinks they have travelled to a parallel world.
 * The Doctor says only real wrestling is in zero gravity with tentacles and magic spells.
 * According to the psychic paper, the Doctor works for the Palace. The Doctor says he hasn't heard that one in a while.
 * In Sutcliffe's mansion, the Doctor plays with an Orrery.

Currency

 * The frost fair costs only six pence to take part.

Food and beverages

 * A bypasser accidentally drops a basket of fruits and vegetables on the Thames.
 * A seller is selling chestnuts just above the stairs to the fair.
 * Food stalls at the fair include:
 * Shish kebab, shish squid, shish chicken, ox cheek, Lapland Mutton, sheep heart etc. stalls.
 * Fish pie, meat pie, chicken pie etc. stalls.
 * Gingerbread stalls.
 * Gin stalls.
 * The Doctor steals fish pies from a con-artist.
 * Nardole has made tea and adds coffee to give it flavour.

Species

 * A giant sea serpent is held chained beneath the Thames. After it broke free, the icy River cracked and ended 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.
 * The Doctor mention fireflies and glow worms.
 * The excrement from the sea serpent is used as fuel by Sutcliffe's people.

People

 * The Doctor jokes with Bill about an imaginary person called "Pete" who stepped on a butterfly and got erased from history.
 * Watermen are in charge of keeping order at the frost fair.
 * Bill says she was a skittles champion two years in a row.
 * Sutcliffe is racist and sexist.
 * Sutcliffe has a lot of working men patrolling all night.
 * The workplace has a dredger-in-chief overlooking the work.
 * Sutcliffe has a manservant.
 * Sutcliffe greets the Doctor as "Doctor Disco, from the Fairford Club".
 * The Doctor refer to the sea serpent as "Tiny", "the loch-less monster" and the "not-so-little mermaid".

Locations

 * The TARDIS lands on the Blackfriars Bridge next to New Lime Wharf.
 * The fair stretched from Blackfriars to London Bridge.
 * The Doctor and Bill are heading towards Freezeland Street.
 * Kitty worry that the Doctor will take her and the other urchins to the Magistrate.
 * Sutcliffe has a workhouse upriver where his men work with the serpent's excrement.
 * The Doctor questions whether the chief dredger checked that no one followed the transport carts all the way to Hampton. He says he checks all the way to the steel mill.
 * Bill worries the serpent will eat people off the Southbank and half of London and that they've doomed Greenland.

Story notes
Model Unit Supervisor: Mike Tucker Senior VFX Technician / Sculptor: Alan 'Rocky' Marshall Senior VFX Technician: Colin Mapson Portrait Sculptor: Stephen Mansfield Director: Bill Anderson Producer: Nikki Wilson Line Producer: Steffan Morris Underwater DoP: Rob Franklin Grip: Sam Reeves Gaffer: Mark Hutchings Best Boy: Andy Gardiner
 * The read-through for Thin Ice took place on 18 July 2016, and filming on the episode began on 1 August.
 * Steven Moffat joked in an interview that the intro to EastEnders was always about a giant snake, a reference towards the view of the River Thames from above, which makes it look like a serpent.
 * Spider is one of the few child characters to actually be killed on-screen throughout the history of the program.
 * For shots involving the Doctor falling below the ice in his diving gear were created by The Model Unit using a miniature 1/3 scale puppet inspired by a similar effect in ’s film . To create Capaldi's head, Stephen Mansfield was invited back to the production to sculpt the feature. Mansfield had previously worked on the show during the era of Sylvester McCoy, making such creatures as the Destroyer and the Haemovores. The members of the team who worked on the effect, as listed on the Facebook page of the Model Unit, are:
 * Kitty warning Spider about how they'll be transported if caught is a reference to how England would transport convicts to Australia contemporaneously.

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 there before, "a few times". (AUDIO: Frostfire, PROSE: The Frozen, TV: A Good Man Goes to War)
 * He has also previously visited a differently frost fair. (PROSE: Silhouette)
 * The Doctor gives Bill the same set of directions to the TARDIS wardrobe that the Ninth Doctor gave Rose. (TV: The Unquiet Dead)
 * 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 speculated that they had travelled to a parallel world. (TV: The Age of Steel)
 * 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 says he's getting used to being asked how he finds people. (TV: Partners in Crime, The Sontaran Stratagem)
 * 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 reminds Bill that he is her tutor. (TV: The Pilot)
 * The Doctor asked Bill if she noticed he was "down with the kids" after entertaining the urchins. He previously noted his ability to fit in. (TV: School Reunion)
 * The Doctor has previously used the "conjection/solution/conclusion" manner of working out a problem. (TV: Listen)
 * 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)
 * The Doctor uses his psychic paper. (TV: The End of the World et al.)
 * Nardole reminds the Doctor of his oath. (TV: The Pilot, Smile)
 * Nardole reminds the Doctor he said he wouldn't be going off-world. (TV: Smile)
 * Nardole has made tea for the Doctor. (TV: 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 again leaves a historical decision up to his companion. (TV: Kill the Moon)
 * The Doctor is asked how many people he has seen die (TV: Journey's End) and personally killed. (TV: The End of the World, The Day of the Doctor, The Time of the Doctor, Hell Bent) 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)
 * The Doctor and Bill returns to the Doctor's office. Bill remarks that it looks the exact same, from the cup of previous sonics, wooden raven and family photographs to the books, the busts and the placing of the chairs. (TV: The Pilot)
 * Bill uses search-wise.net to look for the serpent incident. Rose Tyler used the same web to look up the Ninth Doctor. (TV: Rose)
 * Nardole checks on the vault. (TV: The Pilot)
 * Someone behind the vault doors knocks three times repeatedly. The last row of knocks is 4 times. The Doctor previously said knocks were weirdly in rows of 4. (TV: Hell Bent) was previously plagued with a drumming sound in 4 beats, and later a prophecy developed around the Tenth Doctor's death being preceded by 4 knocks. (TV: Utopia/The Sound of Drums/Last of the Time Lords, Planet of the Dead, The Waters of Mars, The End of Time) The  Midnight entity also used 2, 3 and 4 knocks when inspecting the Midnight Crusader Tours' shuttle bus. (TV: Midnight)

DVD releases
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Digital releases
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