Inspector Cockrill has finally booked a holiday, destined for a Mediterranean tour with a motley crew of fellow vacationers. By the time they have reached the island of San Juan el Pirata off the Italian coast, the tour group is a bubbling pot of rivalries and tension between friends and lovers, threatening to boil over into violence in the scorching summer heat. As six holidaymakers relax at the beach under Cockrills watch, the seventh of their number is slain in the hotel. Believing that the murderer must have been one of the beachgoers, Cockrill faces what looks like an impossible puzzle - one that must be solved before the islands own police force delivers the wrong suspect to their doom.