• Jodie Whitaker (The Doctor)
• Mandip Gill (Yasmin Khan)
• John Bishop (Dan Lewis)
• Aisling Bea (Sarah)
• Adjani Salmon (Nick)
• Pauline McLynn (Mary)
• Nicholas Briggs (voice of the Daleks)
• Barnaby Edwards, Nicholas Pegg and Jon Davey (Dalek operators)
• Jonny Dixon (Karl)

New Year's Eve 2021: Sarah is working, by herself, at a self-storage facility. She is not happy as her plans have been scuttled once again by her boss, Jeff. Nick arrives, as usual, to store an item in the space he has rented. Though, perhaps he is more interested in Sarah than she realises or cares.

The Doctor activates the reset mode of the TARDIS as part of a clean-up after the Flux. She, Dan and Yaz have seven seconds to get out...and enjoy the beach. Except, as they exit the TARDIS the trio find themselves in a self-storage facility. One further arrival appears: an execution Dalek with a mission to exterminate the Doctor. It is a New Year's Eve that the five people will not forget...

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• Jodie Whitaker (The Doctor)
• Mandip Gill (Yasmin Khan)
• John Bishop (Dan Lewis)
• Crystal Yu (Madam Ching)
• Marlowe Chan-Reeves (Ying Ki)
• Arthur Li (Ji-Hun)
• Craig Els (Chief Sea Devil)
• David K.S. Tse (Ying Wai)
• Jon Davey, Simon Carew, Chester Durrant, Richard Price, Mickey Lewis & Andrew Cross (Sea Devils)

China 1807: a coastal village is visited by the pirate queen, Madam Ching. One man realises she is there for the statue: she must be stopped and if he fails then the duty passes to his son, Ying Wai. As the pirate hacks away at the base of the statute, cracks begin to appear in the statue itself. The man approaches her, putting a sword to her neck, telling her to stop - she does not know what she is doing. As the two face each other, swords drawn, the statue shatters and both are flung to the ground. The man turns to look up at the Sea Devil that has emerged as it raises it's sword.

The Doctor, Yaz and Dan arrive on the beach. A localised geomagnetic disturbance has drawn the TARDIS off course. Screaming nearby sends them running towards the village where they find most of the villagers slain. Confronting a lone Sea Devil, the Doctor learns that it is looking for something. The Doctor's attempt to trap it fails, and Sea Devil gets away into a sailing ship converted into a flying ship.

Madam Ching explains that has been search for the lost treasure of the Flor de la Mar. Legend has it that the ship bearing the treasure sank near this village and a clue was embedded in the statue. That statue however, was a trap for an ocean demon - the Sea Devil, which has now been released. Resuming her quest, Madam Ching has two stowaways on her ship - Dan and Ying Wai. Annoyed that Dan has wandered off, the Doctor informs Yaz that she intends to travel back in time to the last known possible location of the Flor de la Mar.

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• Jodie Whitaker (The Doctor)
• Mandip Gill (Yasmin Khan)
• John Bishop (Dan Lewis)
• Sacha Dhawan (The Master)
• Janet Fielding (Tegan Jovanka)
• Sophie Aldred (Ace/Dorothy)
• Jemma Redgrave (Kate Stewart)
• Jacob Anderson (Vinder)
• Patrick O'Kane (Ashad)
• Joe Sims (Deputy Marshall Arnhost)
• Sanchia McCormack (Train Marshall Halaz)
• Alexandra (Anna Andresen)
• Richard Dempsey (Nicholas)
• Joe Slovik (Messenger)
• Nicholas Briggs (voice of the Daleks and voice of the Cybermen)
• Barnaby Edwards and Nicholas Pegg (Dalek operators)
• David Bradley, Peter Davison, Colin Baker, Sylvester McCoy, Paul McGann, David Tennant, Jo Martin (The Doctor)
• Bradley Walsh (Graham O'Brien)
• Katy Manning (Jo Jones)
• Bonnie Langford (Mel)
• William Russell (Ian Chesterton)

An all-frequency emergency transmission is sent by the Toraji Transport Network: they are under attack and being hijacked. The hijackers are Cybermen, but when it seems they are easily taken off, the crew discover these Cybermen can regenerate - they are Cybermasters. A call from the Doctor advises the crew and the passengers to get to safety: she is preparing to board and assist. The Cybermasters are after the cargo: a child. Despite her best attempts, the Doctor fails and the Cybermasters get away with the child.

In Siberia 1916, Rasputin is summoned to the Winter Palce: the Tsarevich has been taken ill.

London 2022, Ace is visiting a museum and notes that a recently restored painting has been taken away for further restoration. Calling Tegan, Ace explains that 15 paintings have all been taken away, simultaneously, for restoration work. Tegan is in Romania: three seismologists were last seen investigating an earthquake in a volcanic chain near the Carpathian mountains. Even more puzzling is a present that was waiting for her when she arrived, supposedly from the Doctor. However, the present did not contain a Russian doll but a model of a Cyberman, something which stirs memories that Tegan is not fond of.

The Doctor, Yaz and Dan return to Earth where Dan decides its time for him to remain. As the Doctor and Yaz adjust to his departure, a message is received from a Dalek, asking to meet and even offering a chance to destroy the Daleks, otherwise the Earth will be destroyed. On top of this, the child the Doctor is trying to locate is on a planet very near to Earth in 1916.

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