The team reinvestigates the suspicious murder of Craig Rossiter, and find themselves at the centre of a plot involving witchcraft, magic and curses.

Rossiter, a librarian, had been a member of a coven when he died 10 years ago. There were few clues as to the cause of his death. The team has to infiltrate the coven and speak to other members in order to get answers. But the investigation leaves them all feeling very uneasy.

With barely any leads, Sandra takes the team to Richmond Park, the scene of Rossiter's death. A young woman, Grace Woodford, appears unexpectedly at the scene, clearly distressed and accompanied by her therapist. Also part of the coven, Grace remains traumatised by Rossiter's death although has little memory of the sequence of events leading up to it. But Grace is able to provide the names of other coven members, including Rhoda Wishaw, a white witch living in Ashdown forest.

The case takes another sinister turn when Brian visits the library where Rossiter used to work and makes a startling discovery.