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Once, Upon Time, prefixed with Chapter Three in the title sequence, was the third episode of series 13 of Doctor Who. It formed the third chapter of the six-part serial Doctor Who: Flux.

This chapter saw the Thirteenth Doctor revisiting lost memories in her own time stream. As such, it re-introduced the Fugitive Doctor, and began to piece together how she fits in with the Siege of Atropos and the origin of the Flux, long ago. It also connects the Division, and their creation of the planet Time, to the ending of the Dark Times, linking these new revelations to the expansive mythology of the existing Doctor Who universe, establishing the concept of Time as naturally chaotic and unstable.

As the episode focused in on each character's history, Once, Upon Time also shone light on Vinder's story, including how he came to be on Outpost Rose, and what will be his main motivation: reconnecting with his pregnant wife, Bel, who is shown making her own way to find him. Bel's storyline in the episode also highlights the Flux's impact on the wider universe, with many worlds overtaken, and provides an anchor for the audience to understand what the Great Disruption has done to local time.


Atropos has fallen, once again. The Doctor has thrown herself into a time storm in a desperate bid to save her friends. As Time itself comes apart, she finds much more than she bargained for.

All four are lost, together, in memories: past, present, future. So many roles they play. So many choices they have endured. And now, what happened once has come again.


Walking through the mossy ruins of a castle on a mostly empty planet, a woman named Bel narrates her story. She tells an unseen loved one that she is hiding in the Dalek Sector of the universe in the aftermath of the Flux attack, narrowly avoiding capture while trying to make sense of the corrupted time and space. However, she is unafraid of them, which she notes as she finds two people in a field being hunted down and instantly disintegrated by a swarm of bright blue floating particles. She believes they are tracking down survivors but swears that nothing will stop her from finding the one she loves.

Inside the Temple of Atropos, the Doctor thinks extremely fast as Swarm continues his threats to kill Yaz and Vinder by making them take the place of the Mouri. Noting only "one massive risk" left, she leaps out of Swarm's way, pushing Dan and herself on the remaining two pedestals. After using her sonic screwdriver, the four wake up floating in an area of rapidly fluctuating purple space, which the Doctor calls the middle of a time storm, allowing them to shelter and hide from Swarm. However, the group are sucked away one by one before she can finish, and the Doctor is the last to disappear after witnessing a vision of a Weeping Angel.

The Doctor comes to, wearing a darker coat than normal, in the middle of a dusty battleground, holding a stakeout on a nearby building alongside Yaz, Dan, and Vinder, each behaving uncharacteristically militarian and equipped with large weapons. They give the Doctor updates on aerial shelling bombardments and the status of hostages, but she quickly snaps out of her attitude and asks where she is. Yaz simply injects her to counteract the 'temporal hazing' so they can end the Siege of Atropos. The Doctor realises she is outside the temple before returning to her commander-like ways and prepares to give her friends orders.

Elsewhere, Dan materialises in Liverpool, meeting Diane and carrying a coffee for her. As they talk, however, they teleport to different areas of the city, with only Dan noticing anything strange. Although he notices the swarm of blue particles, they again teleport somewhere else, this time at night, before he can comment on them. As Dan explains about having once been jilted by his fiancée fifteen years ago, he realises he is reliving a past conversation and suddenly Diane disappears, replaced by a Passenger form. He also sees a faint vision of the Doctor, explaining she is trying to help but is busy.

Next, Yaz appears in the passenger seat of her police car, parked up during a night-time break. As Yaz listens to her supervisor chatting, she realises she has been replaced by the Doctor but quickly switches back to the correct person. Yaz is confused further upon seeing a Weeping Angel in her wing mirror and rear-view mirror, but nothing is there. The other policewoman is again replaced by the Doctor, who explains she is trying to break into their time streams but is having trouble doing so.

Vinder finds himself reliving the memory of being granted an exceptional honours award at his planet's military, except that his officer is replaced by Yaz. He briefly realises that he has been here before but is interrupted by another distant vision of the Doctor. Vinder's officer warns him about the post of his new promotion - acting as the guard of the Grand Serpent - and as the two shake hands, she briefly flickers back to being the correct man for the memory.

The Doctor's vision of breaking into the Temple of Atropos continues, but after she announces their intention to locate the Ravagers, she appears back in the time storm, speaking to three giant Mouri. They explain that time is playing games with them and will overcome her even if she is trying to save her friends' lives. Inside the temple, the Doctor shouts to the Ravagers to surrender, but when she sees her reflection, she faces up to the Fugitive Doctor, both of whom are surprised to see each other. The Fugitive Doctor does not recognise her, leading the Thirteenth Doctor to realise she is in a distant memory of when she was her. Being interrupted by her team, Yaz calls Dan "pretty smart for a dog", leading the Doctor to again question who they are. Vinder, however, promises that after this mission, she will be free of having to do any more. In her reflection, the Fugitive Doctor simply tells her that she has a lot to figure out.

Inside a series of tunnels, Dan finds himself running from laser fire, coming face to face with Joseph Williamson, who is also holding a laser weapon. Williamson asks him why he is disobeying his task, leading Dan to realise he is "very, very far" from Liverpool. The blue swarm of particles narrowly dodges them, but Williamson says that he was not shooting at them. Teleporting back to Liverpool, a projection of the Doctor tells Dan that he is hidden in his time stream while she works on the Mouri, but with time breaking up, she is facing a lot of problems.

Bel continues to narrate her journey in the aftermath of the Flux. Having stolen a Lupari ship, she barely makes it out of the Dalek Sector and lands on a different rocky planet, only to quickly learn that it has been taken over by armies of Cybermen. She tries to remember her missing love's words about always moving forward and holds a small device with a happy face that she calls Tigmi close to her.

Vinder finds himself reliving a memory of his first day as guardian of the Grand Serpent, inside a plush yet dark room with wide views of interstellar space. He tells Vinder that he should protect him and record his vital meeting with Alforia for an interplanetary protection deal. However, Vinder is quickly told off for speaking out of line and is forced to be silent. As he wishes not to relive this day, Vinder looks across and sees one of the guards replaced by Yaz.

Yaz next appears on a sofa next to Sonya, who is trying to learn how to play a video game to impress a boy (even though Yaz doesn't like playing them). However, Sonya quickly flickers into the Doctor, who explains the situation to Yaz. Yaz points out that she is in the wrong house and does not know these events, leading the Doctor to conclude that something is wrong with her time stream, which is confirmed when a Weeping Angel appears in the horror game they are playing. Quitting the game does not get rid of it, and the Doctor begs her to avoid it as she is pulled away. Yaz eventually stops it by destroying the game console, baffling Sonya.

The Doctor finds herself back on Atropos in the past again, facing up to Old Swarm and Azure. She tries to force them to surrender, with herself flickering between the Thirteenth and Fugitive Doctors as she does so, but they ignore her. As Swarm confirms that she is part of the Division, he explains what a Passenger is: an endlessly large living prison, with five of them each holding hundreds of thousands of hostages. Swarm destroys one, killing all within. Swarm states that "time shall never surrender to space", calling it heresy, just as the Mouri are connected. The Doctor proudly exclaims that one of the Passengers is theirs, holding the Mouri, ready to harness time, just as her team arrives and captures Swarm and Azure, teleporting them away. In the time storm, the Doctor tries to convince four of the Mouri to hide inside a Passenger as they did in the past, to solve the new problem in the same way.

Inside the Lupari ship, Bel narrowly escapes the Cyber Zone and starts searching for a new place to land. However, her ship is invaded by a handful of Cyber-Warriors and Bel bursts into action, shooting down most of them amid a hail of shots and incapacitating the final one. She asks it what is happening with time and what their mission is, leading her to realise that all the surviving monsters just want to take over as much of the surviving universe as they can. When the Cyberman asks what her mission is, she simply replies 'love' and shoots it dead.

In Vinder's memory, the Grand Serpent reaches the end of his deal with the Alforians but forces Vinder to turn off the recording before he finishes. Without being covered by evidence, the Grand Serpent tells the Alforians to hand over five missing dissidents and for the other four, family members of his closest critic, Frey Sampor, to be killed in an "unexpected tragedy", shocking and startling Vinder. Sometime later, he reports to his officer, still replaced by Yaz, about the Grand Serpent's actions. Aware of the repercussions he will be faced with, Vinder begs not to have to relive it, but goes ahead and submits the report regardless. Thus, he finds himself on Observation Outpost Rose, allowed to record only one message: "I love you".

The Doctor continues recalling the siege of the temple, realising that the person on her team replaced by Dan was Karvanista. They choose to rescue the hostages and escape. Back inside the time storm, the Mouri tell the Doctor that they are ready for her to return everyone to their own time, but refuses, desperate to find out more of her history. However, the Mouri deny this, knowing she will die with the effort, and they force her out, screaming.

However, instead of returning to the present-day Temple of Atropos, she instead appears in a mysterious space station, with an old woman named Awsok telling her to give up her efforts. Awsok explains that the damage to time has been done, "as intended", with the Ravagers being introduced to willingly contaminate time, just as the Flux was created to destroy space. Awsok believes that the Doctor is at fault, but she does not follow, eventually being forced out and sent back to the temple.

Despite yelling that she needs to be put back, the Doctor is powerless to, even when discovering that her plan to return the Mouri and save Yaz and Vinder was successful. Swarm and Azure taunt her, describing how they knew what she would do, and summons the blue particles, named the Time Force. Swarm goes on to reveal that one Passenger includes Diane, infuriating Dan and convincing Vinder to help the Doctor's group out. Swarm simply taunts that he wants "to reign in Hell" and teleports himself, Azure, and the Passengers away. The group return to the TARDIS, which Vinder identifies after finding it to be bigger on the inside. She stubbornly ushers everyone inside to look for answers.

Elsewhere, sat by a lonely campfire, Bel watches Vinder's single message of love to her. She wonders to Tigmi if he may look different after so long but promises that she and his currently unborn child will find him soon. Meanwhile, the TARDIS group lands on Vinder's home planet, finding it all but destroyed to ruins by the Flux. The Doctor offers to help him find Bel, but he insists he must do it alone, so she gives him a phone as a direct line to her. The Doctor, Yaz, and Dan dematerialise in the TARDIS and Vinder and Bel, separated by untold distances, promise to find each other, whatever it takes.

Inside the TARDIS, Yaz checks her phone as suddenly, a Weeping Angel appears on the screen. She drops it in shock, and it jumps out of the screen, into the control room itself. As the Doctor tells her friends to not blink, it starts making the lights flicker, causing it to jump around the central console. Realising that it is piloting, the Doctor tells her friends, terrified, that "the Angel has the TARDIS."


Uncredited cast[]


General production staff

Script department

Camera and lighting department

Art department

Costume department

Make-up and prosthetics



General post-production staff

Special and visual effects


Not every person who worked on this adventure was credited. The absence of a credit for a position doesn't necessarily mean the job wasn't required. The information above is based solely on observations of the actual end credits of the episodes as broadcast, and does not relay information from IMDB or other sources.


Story notes[]



"Masked Ravager Guards" from the original cut

  • The original episode had creatures of the Ravager race known as "Masked Ravager Guards" appear in the Temple of Atropos scenes, but they were cut in the final edit.[7]


  • Though the title sequence gives this episode as Chapter Three: Once, Upon Time, other sources have differed on the prefix, naming this episode Flux: Once, Upon Time instead.


  • The credits of this episode cemented the term "Fugitive Doctor" — gained from the title of the episode where this incarnation first appeared, Fugitive of the Judoon, and widely used in Doctor Who fandom up to this point — as a DWU term.
  • This episode firmly establishes the Fugitive Doctor as a past incarnation, something which had been left ambiguous since her debut. Specifically, it places her near the end of the Doctor's association with the Division, adding extra weight to her decision to run away by TV: Fugitive of the Judoon.
  • A Weeping Angel shows up in the video game Yaz and Sonya are playing in reference to VR game The Edge of Reality, with its appearance later on Yaz's phone, from which it emerges, references the iOS game The Lonely Assassins. Both games were released earlier in 2021.
  • The video game Yaz and Sonya play bears a resemblance to Resident Evil.


  • Overnight: 3.76 million[8]
  • Consolidated: 4.67 million[9]

Filming locations[]

to be added

Production errors[]

If you'd like to talk about narrative problems with this story — like plot holes and things that seem to contradict other stories — please go to this episode's discontinuity discussion.
  • The BBC iPlayer subtitles during the Next Time trailer incorrectly names Peggy as "Maggie".
  • On the DVD version, during the Next Time trailer, Claire, for some unknown reason, says "28th November 1967" instead of "21st November 1967" which she said in the original broadcast version.


Home video releases[]

DVD and Blu-ray release[]

  • Once, Upon Time was released, together with the five other episodes of Doctor Who: Flux, on DVD and Blu-ray in region 1/A on 15 February 2022, in region 2/B on 24 January 2022 and in region 4/B on 16 March 2022.

Digital releases[]

  • In the United Kingdom, this story is available on BBC iPlayer.


External links[]