Coming back from work by night, shy watchmaker Tommaso runs over a girl with his car, luckily without serious consequences. Next day he finds her waiting for him at his door. She asks him for help, as she can't remember anything prior to the incident.

A series of random suicides in Rome, Italy are attributed to a heatwave, but a young pathologist named Simona—who is working on a thesis about murders disguised as suicides—suspects otherwise. When a young girl associated with Simona's playboy father ends up dead in another apparent suicide, Simona teams up with the girl's priest brother to prove she was murdered and track down the unknown serial killer.

Don Giovanni is a handsome gentleman whom women find irresistible; he is equally successful in overcoming his male rivals. Among these, however, is a commander whom he killed in a duel and who returns to torment him in the form of a statue.

Franco Riva, a geologist who works in Ivory Coast, suddenly returns to Italy, to Genoa, to see his girlfriend, Claudia Fiori, of whom he has not heard for some time. Riva gathers various information about his fate. The concierge of her apartment, which she left two months ago, claims that Claudia has rented a house on the Riviera and got married. Instead, Claudia's sister, Laura, excludes that she might have gotten married without telling her anything and shows the man a postcard that Claudia sent her from Stockholm, where she told her that she was moving for the company where she worked. But the owner of the company, Piero Ricci, denies even the existence of a branch in Stockholm. So Franco turns to the police...