While on a visit to Amsterdam, Jessica meets up with fellow novelist and old friend Nigel Allison. When Allison goes missing, Colin Biddle, who claims to be Allison's publishing liaison, try to convince her that nothing is wrong. Jessica soon realises that both Nigel and Colin are secret agents, and despite Colin's request for her to stay out of it, Jessica investigates Allison's disappearance and soon convinces a previously reluctant inspector that there is something terribly wrong. At the same time, Philip and Lydia de Kooning are trying to make a deal in diamonds, and when Philip turns up dead after Jessica gets a note supposedly from him, Jessica is the prime suspect in his murder.