An elderly couple, both religious fanatics, barricade themselves in their home and begin shooting from the windows for no apparent reason, until Montalbano's men finally succeed in disarming them.There seems to be no justification for the couple's insane actions, but police find a strangely disfigured inflatable doll inside their home. A few days later, an identical doll is discovered in a rubbish bin and Montalbano has a bad premonition.Soon enough, a series of strange occurrences develops - disquieting letters bearing riddles are delivered to Montalbano at Vigata police station, while a young woman is reported missing. A disturbed maniac is playing a macabre game of treasure hunt with the inspector and the riddle must be solved before it's too late.

The yacht of a wealthy woman docks at Vigata's harbour as a disfigured body is discovered at sea. Coastguard Laura Belladonna is assigned to the case to assist Montalbano and the two soon become close. The investigation casts doubts on the motives and sincerity of the yacht's crew and Montalbano begins to suspect that there may be more to the story they have given him.

A series of burglaries take place at the houses of wealthy Vigata residents. One of the victims is a beguiling young bank manager called Angelica, to whom Salvo finds he is soon attracted. As the investigationprogresses, Montalbano starts to suspect that the burglaries might be a cover for something rather more sinister.