Five skeletons are unearthed on Rat Island, an uninhabited island owned by the Ministry of Defence. Among them are the remains of a woman dubbed 'Quintessa' by the detectives, who was murdered sometime in the 1980s. Then Horton receives a mysterious phone call from Adele Goldsby, the daughter of a Portsmouth politician who died in suspicious circumstances. She says she has something important she wants to tell Horton and that they must meet on the...