It's summer in New York, and the city is boiling. Unable to stand the heat, Dan Fortune's girlfriend Marty asks him to pawn her diamond ring in order to buy them a few weeks by the seashore. Fortune does as told, but picks up some business while at the pawnshop. There he meets Claude Marais, brother of the pawnbroker and veteran of the humiliating French defeats in Vietnam and Algiers. Fearing her husband's life is in danger, Claude's wife hires Fortune to guard him against a mysterious German with a years-old wartime grudge. Because money is tight, Fortune violates his own policy of avoiding suspicious cases, and agrees to spend a night standing guard outside Claude's hotel room. In the morning Claude is fine, but the pawnbroker hangs from a rope in his shop's back room. To avenge the pawnbroker, Fortune's vacation will have to be postponed.