When Sir Colin and Sally Edensor approach Cormoran Strike and Robin Ellacott, they are desperate to reconnect with their estranged son, Will. The Edensors enlist the detectives to gather evidence to discredit the Universal Humanitarian Church, a religious cult who have indoctrinated Will and siphoned off his trust fund.
Led by the charismatic Jonathan Wace, the church is shielded by a charitable façade, celebrity backers and aggressive lawyers who have silenced critics. To investigate allegations of ill-treatment and abuse, Robin goes undercover at the cult's secluded Norfolk headquarters, Chapman Farm. At the centre of the church's twisted mythology is the story of the Drowned Prophet, Daiyu, believed to be divinely reincarnated.
While Strike gains valuable insights from former members on the outside, Robin finds herself facing unprecedented psychological and physical duress on the inside. Solving the mystery of the Drowned Prophet's death becomes key to the case but leads the detectives into dangerous, unchartered territory.