Myfanwy and Farrier quickly discover how dangerous life is outside of the Checquy, while Grantchester runs out of options. Myfanwy chooses between her freedom and Farrier's life.

After a terrifying prophecy, Myfanwy's desperation leads her to a place to trust in a powerful enemy. But when her plans go awry, she is forced to run for her life while her memory slips away.

While Myfanwy returns to her childhood home, Farrier faces consequences at the Checquy and Monica copes with the discovery that she was betrayed by Marcus.

Myfanwy and Monica work to extricate a young EVA, while Gestalt's suspicions of Myfanwy lead to a confrontation. Farrier is suspended, only to seek powerful revenge.

While Myfanwy uncovers a twisted relationship with her psychiatrist, Monica and Gestalt scour London for a missing EVA who escaped after auction. Farrier makes a connection with a mysterious prisoner.

Myfanwy discovers a disturbing clue to her past, Farrier searches for a scapegoat for the bankside murders, and Monica goes undercover to attend an EVA auction.

While Myfanwy revisits the crime in search of her past, Monica discovers a dark truth about one of the victims - her lover and fellow agent. One of Myfanwy's dead attackers disappears from the morgue.

A woman suddenly wakes up with no memory of who she is and a litter of dead bodies around her, but as she investigates what happened, she is thrust into the world of an English paranormal secret service known as the Checquy.