On a sunny seaside August morning, a woman on maternity leave spots a body wedged in rocks on a Scottish beach. Gavin Ayre's riding gear sparks the assumption that he had been thrown by a panicked horse ... until an autopsy reveals this was no accident. Soon it becomes clear that Ayre's life was as big a mystery as his death. Detective Superintendent Harold 'Sauce' Haddock heads an investigation that is running into the sand, until a link is revealed between the victim and another man in Spain, with a surprisingly similar name. Faced with the twin puzzle Sauce turns to his mentor, Bob Skinner, moved on from the police service to head an international media group. Soon the two friends are at the heart of a multi-layered conspiracy, as they search for the answer to the prime question ... who killed Gavin Ayre?