Twice Upon a Time

Twice Upon a Time was the 2017 Christmas Special of Doctor Who. It was the show's thirteenth Christmas special since its revival and the fourth starring Capaldi as the Doctor. It was also the final chronological appearance of Peter Capaldi as the Twelfth Doctor and introduced Jodie Whittaker as the Thirteenth Doctor in its closing moments.

After a surprise appearance at the end of TV: The Doctor Falls, the First Doctor was an integral part of the special's narrative. Here, he was portrayed by David Bradley, who had previously played the original actor William Hartnell in An Adventure in Space and Time. Archival footage from The Tenth Planet was used to bookmark the First Doctor's place in this story.

Ben Jackson and Polly Wright made a brief re-reappearance in the programme for the first time since their exit in 1967's The Faceless Ones. Bill Potts joined the two Doctors as a Testimony glass avatar. Past companions Nardole and Clara Oswald made similar brief appearances. Rusty, from Capaldi's second episode, Into the Dalek, made his second appearance in Villengard, a location mentioned only once before on television, in Steven Moffat's second television story, 2005's The Doctor Dances.

In early 2018, Murray Gold announced his departure from Doctor Who after twelve years at the Gallifrey One convention his last episode. It was also the final story with Steven Moffat as head writer and the first to include any part written and overseen by incoming lead writer, Chris Chibnall.

While not known at the time, this would also turn out to be the last consecutive Christmas special of the revived series, breaking the streak that began with The Christmas Invasionin 2005. The show would forgo its usual Christmas special in 2018 in favour of a New Year Special at the beginning of 2019.

Synopsis
As the Doctor nears regeneration, he stumbles on his original self, also refusing to change. It takes a captain, a glass avatar and a familiar face to convince the Doctors the universe still needs them.

Plot
The First Doctor nears his end after an encounter with the Cybermen from Mondas. He is freed from his restraints by his companions Ben and Polly, now that the threat is over. However, he is weak, his body beginning to regenerate. Refusing to give in, the Doctor leaves and wanders the South Pole, mumbling to himself that he will not change. Nearing his TARDIS, he hears a voice in the distance yelling in defiance. Seeing a figure kneeling outside his TARDIS, the Doctor asks who the man is. The man claims to be the Doctor. With a smug sense of superiority, the First Doctor tells the man that's not true; "you may be a doctor, but I am the the doctor. The original you might say."

The scene transitions to the Twelfth Doctor as he gets to his feet, shocked to see his past self. The Doctor is delighted at meeting his first incarnation but realises that he is refusing to regenerate; he panics as he doesn't remember refusing to to regenerate the first time or meeting himself. The First Doctor is confused and dismisses his future self as just another Time Lord; he asks if he has come to take back "the ship". The Twelfth Doctor laughs in amusement that his original incarnation still calls the TARDIS "the ship".

The First Doctor then asks what the Twelfth has done to the TARDIS, as its bigger than it used to be. The Twelfth Doctor tells him its from "all those years of being bigger on the inside. You try keeping your tummy tucked in that long", defending his beloved vessel. The Twelfth Doctor questions why his younger self is refusing to regenerate, fearing the consequences the decision might cause. However, the snow suddenly freezes in midair, capturing the pair's attention, as a man dressed in World War I attire approaches them. He seems disorientated and asks the pair if either of them are a doctor. Exchanging a glance with the First Doctor, the Twelfth asks if the man is making some sort of joke.

On Christmas Day 1914, the soldier, a captain in the British Expeditionary Force, lies in a shell hole on the battlefield in Ypres. His revolver is aimed at a German soldier, who also has his sidearm trained on the Captain. Both men realise they will kill each other in self-defence, their respective troops far away in their trenches, unable to assist either of them. Just as the Captain prepares to accept his fate and fire, a wave of energy flows through the field, freezing everything around him. As he exits the hole, a bright light suddenly flashes and encapsulates him. He collapses to the ground in the Antarctic and hearing the two Doctors discussing the static snow, he approaches them.

The scene once more shifts back to the Twelfth Doctor's perspective. A portal of light opens in the distance, and the two Doctors approach it. The First Doctor orders the portal to reveal itself, while the Twelfth Doctor declares that the planet is protected, to the confusion of his first incarnation. However, the light quickly vanishes, surprising the Twelfth Doctor as "that almost never works." The First Doctor returns to the Captain, telling him to enter his TARDIS, and the Twelfth Doctor coaxes him to follow. As they enter, the First Doctor is shocked by the changes to the TARDIS interior, while the Captain is shocked by the room's size. The Twelfth Doctor pulls the monitor over to the First Doctor, telling him his TARDIS is 70 feet away; he then tells him to always remember where he parks as it gets important later.

The First Doctor demands his identity, to which the Twelfth says not to be an idiot as they always know when they meet each other. However, the First Doctor states he does not know, prompting the Twelfth Doctor to show him his hand glowing with regeneration energy. The First Doctor wonders if the Twelfth is his next incarnation, to which the Twelfth says is not the case; he'll become him eventually, "after a few false starts" the Twelfth says with a grin.. The First Doctor mutters that he thought he would get younger when he regenerated, to which the Twelfth snaps that he isyounger than the First Doctor. The Captain interrupts, stating he does not understand what's happening, while examining a VHS tape. The Twelfth Doctor says that's understandable for a soldier from World War I being chased through frozen time by an unknown force. Disturbed upon hearing the Great War being called the first world war, the Captain asks the Doctor what he's talking about; the Doctor simply tells him "spoilers".

The First Doctor notices the Captain's unease, telling the soldier to sit down and orders the Twelfth Doctor to fetch some brandy. He does so, and the First Doctor notices that there is less in the glass than he remembered. The Twelfth Doctor tells him that it's been "rock and roll" over the last 1800 years, so he's entitled to have a glass to steady his nerves. The First Doctor examines the control room, noting that the Twelfth no longer has Polly around since it's so dusty; the Twelfth Doctor begs him to stop saying things like that as it is insulting to women. The First Doctor then notices the Twelfth's electric guitar and amp, which the Doctor tries to pass off as something a companion left behind. However, the First Doctor notes that it is the only thing in the control room that's not covered in dust, making it the Twelfth Doctor's possession.

Suddenly, the TARDIS shakes violently, prompting the Twelfth Doctor to attempt to take off, only to find that the engines are unresponsive. Looking upwards out of the TARDIS doors, he sees large metal claws pulling the TARDIS upwards. Once the TARDIS has stopped moving, the Twelfth Doctor instructs his predecessor to confront their captors. A humanoid glass figure seated at the top of a staircase speaks to the Doctor, addressing him as "The Doctor of War." The figure requests the return of the Captain in exchange for a friend of the Doctor. Much to the confusion of the First Doctor, Billthen exits one of the corridors. The Twelfth Doctor quickly exits the TARDIS to hug her, before slowly pulling away, drawing his sonic screwdriver, and scanning Bill. To her surprise, the Twelfth Doctor demands that she proves herself to be real, as he believes Bill to have sacrificed herself to defeat the Cybermen. Bill insists she is her real self, explaining how Heather had saved her. The Twelfth Doctor asks what happened after Heather saved her and where Heather is now. Bill struggles for an answer.

The Twelfth Doctor decides to confront his captor directly and runs up the staircase. He is slowly followed by his younger self, who questions the need to move so fast. They find an empty chair with several panels behind it. The First Doctor takes to observing the panels, commenting on their extraterrestrial origin. He turns to his older self, his eyeglass dropping from his eye as he notices the Twelfth Doctor wearing sunglasses to scan the panels. He is utterly perplexed by the idea that the sunglasses are sonic. They turn to the chair, where a woman made completely of glass materialises. While the Twelfth Doctor scans the panels with his sonic screwdriver, the original Doctor looks more closely. He berates the Twelfth Doctor for not noticing the asymmetrical features of the woman's face, blaming his use of the sunglasses instead of his eyes. The Twelfth Doctor shyly agrees, and his younger self throws the sunglasses to the ground.

The Testimony proceeds to explain its desire for the Captain back in exchange for Bill, insisting the Doctors return him to them. The Captain, having heard the conversation, exits the TARDIS. He declares they let him be taken, not wanting any harm to come to Bill because of his cowardice. However, the Twelfth Doctor disagrees. Picking up his sonic sunglasses, he races down the stairs, remarking he will find out what the Testimony's purpose is and he will stop it if he doesn't like it. The First Doctor once more berates him for revealing his plan, stating he hasn't a clue who his future self is supposed to be. The Testimony, in an effort to ruffle the First Doctor, reveals the history he is destined to create as a "Doctor of War" by showing how his future incarnations will engage in various battles, which perplexes him.

The Twelfth Doctor presses on with his plan to escape, using the sonic screwdriver to activate the crane which pulled the TARDIS up to take them down, the team jumping onto the chains to escape as well. The Testimony refuses to let them escape, halting the chains and pulling the TARDIS back into the ship. However, as they are a safe distance from the ground, the Twelfth Doctor instructs everyone to jump to the ground.Bill expresses concern about what they will do without the TARDIS but the Doctors reveal they have another, younger version, at their disposal.

They head to the First Doctor's TARDIS, swiftly entering. As she does so, Bill comments on how much smaller it is, causing the Twelfth Doctor to briefly observe the windows before insisting his younger self take off into "deep space, anywhere". While in flight, the First Doctor insists Bill clean the TARDIS only for the Twelfth Doctor to distract him by pointing out the astral map. The Twelfth Doctor uses the sonic sunglasses to access the data banks noting what his predecessor said earlier before placing the shades on the First Doctor. Befuddled, the Doctor asks why he must wear them only for his successor to remark on how much he loves it before taking them back.

The Twelfth Doctor quickly realises the databanks are rather scarce, given the TARDIS is still young. To compensate, he lands the TARDIS at the centre of the universe, Villengard, impressing his younger self at how easily he did such. While searching the area, the Captain is attacked by a creature with multiple little green legs but they save him, both Doctors recognising the creature as a Kaled mutant. The Twelfth Doctor insists Bill wait in the First Doctor's TARDIS to look after the Captain, but Bill blasts him by calling him a "stupid bloody arse", leading to the First Doctor to threaten her with a "jolly good smacked bottom", much to the Twelfth Doctor's embarrassment. Bill tells the Twelfth Doctor to come back alive, to which he replies; "Be here when I do."

The First Doctor fetches the Captain another brandy, realising that was why his successor was missing some. He soon leaves to join his older self, while Bill looks after the Captain, but when she grabs the brandy, her hand is revealed to be glass. While outside on Villengard, the two Doctors rest, discussing their respective regenerations. The Twelfth Doctor remarks they have yet to change because they are in a "state of grace", though he himself finds his body starting to deteriorate. He asks why his younger self halted the regenerative process, unable to remember himself. The First Doctor admits he is "afraid" of regenerating and doesn't like to admit that to anyone. The Twelfth Doctor remarks that technically he still hasn't. Before the Twelfth Doctor can answer the question himself, they suddenly come under attack from a creature in a nearby tower, and only stops when the Twelfth Doctor asks the creature to scan him, announcing; "I'm dying!", before going into the tower. He tells his younger self to wait outside to which he begrudgingly agrees.

The First Doctor observes the area, finding the remains of a Dalek casing. He inspects it as Bill sneaks up on him and begins asking why he ran away. The Doctor insists she return to the Captain but Bill insists, asking what he was running to. Interested by the question, the First Doctor responds that he left to discover why good always defeats evil. Bill suggests it might be because of "some bloke" though the First Doctor doubts such. Bill hugs him, thanking him for his efforts. However, when she pulls away, the First Doctor realises she is a glass avatar.

Alone, the Twelfth Doctor meets with the rogue Dalek Rusty, who has taken refuge from the other Daleks hunting it. He remarks on how he is a "good Dalek" though Rusty continues to fire at the Doctor. The Twelfth Doctor decides to come to a truce to which Rusty agrees by disarming his gunstick. Given access to the Dalek Hivemind, the Doctor learns that the pilot and its ship, known as Testimony, were created on New Earth, designed to extract people from their timelines at the moment of their death, and archive their memories into glass avatars. "Bill" is one such avatar, created from her memories. Time suddenly freezes again, the First Doctor and Bill entering the room. Although disappointed at seeing no evil to fight, the Doctors agree to return the Captain to his timeline.

Upon doing so, the Captain asks the Doctors to keep an eye on his family, introducing himself as Archibald Hamish Lethbridge-Stewart, an ancestor of the Doctor's close friend the Brigadier. The First Doctor assures he will do so, the Twelfth Doctor confirming they did. The Testimony remarks the Captain will not remember the incident and a perception filter will ensure the Doctors are not noticed once time restarts. As time resumes, the Doctors watch as soldiers on both sides begin singing "Silent Night" in their respective languages. Soon, each side disarms their weapons and enters the battlefield, leading the Captain and the German soldier to withdraw their weapons and make peace. The Twelfth Doctor explains to the First that he deliberately shifted the Captain's timeline to the start of the Christmas truce, to ensure his life would be spared. The First Doctor is amazed at the fact that his successor altered time to save both men, leading the Twelfth Doctor to describe the truce as a miracle; the only truce of its kind in history. How everyone at war stopped fighting and was kind to each other. He also explains how "generally the universe isn't a fairy tale, but that's where we come in" and that "it never hurts, a couple fewer dead men on a battlefield." This causes the First Doctor to finally understand what being the "Doctor of War" really means.

With the Captain saved, the two Doctors observe the truce for a time and eventually shake hands. As they do, both Doctors' hands start glowing with regeneration energy. The First Doctor declares that he is finally ready, but the Twelfth Doctor states that his predecessor will have to find out what the Twelfth Doctor decides to do "the long way round." The two Doctors bid each other a fond farewell. The First Doctor returns to his TARDIS and sets the controls to return him to the South Pole in 1986. Overcome by his regeneration, the First Doctor declares "here we go, the long way round" and collapses as his TARDIS returns to the South Pole. Shortly afterwards, the First Doctor regenerates into his second incarnation.

As the soldiers play football, draw and spend the day together, the Twelfth Doctor watches on, saluting the Captain - who briefly bypasses the perception filter, but dismisses him and returns to his trench. Now alone with Bill's avatar, the Doctor adamantly contends she is not the genuine Bill, only for her avatar to explain that memories are what define a person. To help him understand, the avatar restores the Doctor's memories of Clara Oswald then turns into her. Clara greets the "stupid old man", telling him that forgetting her was rude. The Doctor laughs with joy that she's back in his head. Clara reverts back to Bill, who asks the Doctor if he now understands the importance of memory. They are joined by Nardole's avatar who joins Bill in asking the Doctor not to allow himself to die. The Doctor refuses to give the avatars testimony of his life, stating he must be left alone to face his end. They respect his wish and leave after he embraces them both.

The Doctor returns to the TARDIS. He laments how the more he saves the universe, the more it seems to be in need of saving. He briefly argues with the TARDIS, conceding that "they would get it all wrong without me" as he decides to regenerate, saying "One more lifetime won't kill anyone. Well, except me", but not before relaying advice to his next incarnation. He collapses as he does so but manages to return to his feet. Finally ready, the Twelfth Doctor utters his last words "Doctor... I let you go". With that, he takes a last quick gasp for air before he regenerates, the process so violent that the energy ignites the console room as his face and piercing blue eyes start changing, morphing into a younger-looking and rounder one with hazel eyes.

Smoke fills the console room and the Twelfth Doctor's wedding ring falls from a finger it no longer fits. Once the smoke clears, the Thirteenth Doctor stands in silence for a moment, before grabbing one of the console's monitors. Using its reflective surface, she studies her new appearance in stunned wonderment, realising that she has now become female for the first time. Her face cracks into a wide, ecstatic grin as she as exclaims "Oh, brilliant!" at the discovery. Excited, she presses a button on the console. Upon doing so, the TARDIS suddenly suffers multiple failures and, hanging thousands of feet above the Earth, sharply jerks causing the doors to face the ground. The Doctor tries to hang on but the doors open threatening to suck her out. As the Doctor grabs the console, the ship continues to shake, sending all of her books and papers flying out the open doors. The Doctor tries to close the doors, but the time rotor shatters and the panel she's holding onto breaks away, sending her falling out of the ship. In freefall towards the Earth below, the Doctor watches the inside of her TARDIS become swamped by flames before vanishing from sight as she plummets through the clouds...

Cast

 * The Twelfth Doctor - Peter Capaldi
 * The First Doctor - David Bradley
 * Bill Potts - Pearl Mackie
 * The Captain - Mark Gatiss
 * Clara Oswald - Jenna Coleman
 * Nardole - Matt Lucas
 * Helen Clay - Nikki Amuka-Bird
 * German Soldier - Toby Whithouse
 * Polly - Lily Travers
 * Ben - Jared Garfield
 * Voice of the Daleks - Nicholas Briggs