While on detachment to the Lancashire police, DI Lynley investigates the apparent murder of the Reverend Robin Sage who is found on a rural path, where he was presumably walking home. The autopsy reveals that he was poisoned with wild hemlock. He had dinner the previous evening with Juliet Spence who was also violently ill through the night, but survived the poisoning. Juliet is involved in a relationship with PC Steve Shepherd, son of the local DCI Kenneth Shepherd and it is apparent that Juliet's teenage daughter, Maggie, is not pleased with her mother's choice. Uncovering a false identity is central to solving the crime. Lynley meanwhile has fallen in love with Helen Clyde, but can't quite bring himself to do something about it. DS Havers is dealing with the aftermath of having placed her aging mother in a care home.