Rigsy (Jovian Wade), a street-artist, contacts the Doctor (Peter Capaldi) and Clara (Jenna Coleman), asking for help. There is a number tattooed on his neck, counting down to zero. He has no memory of how he got it. They trace his movements to a trap street (A fictitious street put on maps to trap copyright infringers) in present-day London that houses extra-terrestrial refugees, using telepathic alien worms to appear human.
Me (Maisie Williams), the Viking girl become immortal because of the Doctor, explains that she sentenced Rigsy to death because he murdered Anah, a two-faced Janus. The tattoo is a chronolock. When it gets to zero, a quantum shade like a raven will kill him. Me allows the Doctor and Clara to prove Rigsy’s innocence, if they can. Clara takes the chronolock onto herself in the belief that the Doctor will not let her die.
They meet Anah’s psychic daughter Anahson (Letitia Wright) and learn that Me used Rigsy to bring the Doctor to Trap Street because Me fears somebody or something unknown. The Doctor discovers that Anah is still alive and can be released with the TARDIS key. However, the Doctor is transported away to keep the street safe from Me’s dangerous allies. Me demands the Doctor’s will, called the Conversion Dial.
Me goes to remove the chronolock from Rigsy, only to find that Clara has it. But Clara broke the contract with the shade in power over the lock and she cannot undo it. The Doctor angrily threatens Me and demands that she save Clara, but Clara calms him down. She asks the Doctor not to be a warrior, but a doctor. She decides to face death as nobly as Danny Pink, her lover did. She says goodbye and steps into the street to face the shade, in the form of a raven, and it kills her. The Doctor warns ME to keep away from him in the future.
On the trap street live a Sontaran, a Judoon, an Ice Warrior, and an Ood caring for a Cyberman. The street looks very much like Diagon Alley in the Harry Potter films, or Neil Gaiman’s Neverwhere, with Peter Capaldi. A poster on the wall pictures a flux capacitor and the writing says DeLorien in Aurebesh, a language used in Star Wars. This is the third time Clara dies. She is the first companion to die on screen since Adric in the Peter Davison years. Clara’s bisexuality is confirmed in that she had an affair with Jane Austen. Me/Asildr, a Viking, brings about Clara’s death through a raven, a symbol of Death for Vikings. Maisie Williams is famous for her role in Game of Thrones, which featured a three-eyed raven. A painting by Rigsy on the TARDIS at the end is based on a publicity photo for Jenna Coleman’s convention appearances.