Like all the criminal messes Crang has ever found himself caught up in, this one begins in perfect innocence. As Crang is leaving for a holiday on the French Riviera with his movie-critic girlfriend, Annie, his rich-as-Croesus former father-in-law appears to ask if he’d mind checking up on an errant family member who is said to be hanging out in Monaco. Crang says he’ll do the favour, a decision that drops him into a series of ever-tighter spots on the CÒote d’Azur. Crang and Annie enjoy the Riviera’s pleasures, but lurking in the background, gathering menace, is a piece of elaborate fraud and murder. Crang has no choice except to solve all the riddles, nail the murderer and, if he’s adroit enough, eventually tip the scales of justice in the good guys’ favour.