Paolo, a journalist, has just arrived in Los Angeles from Italy for a new job when he is attacked by two men who want to know where his old childhood friend Giulio Lamberti is. When the two leave, Giulio shows up and tells that someone wants to kill him, that he has a diary and that the next day he will let him know everything. But the next day he dies in a car accident. Paolo begins to investigate, starting from his wife Luisa and discovers that Giulio was no longer the man he had known, idealistic and attached to the family. After being hired by International Chemical he had begun to lead a loose life, going so far as to blackmail some International Chemical executives when they wanted to fire him. Amidst a thousand difficulties, Paolo continues the investigation.