Without warning, Mélie disembarks on the cargo ship where her father has the sailor's blues. He remembers his drifts and his friend Max who used to get him into some crazy situations. He remembers Alice and Luc whom he decided to avenge. He has his grenade ready. But Melie has just arrived.

Doctor Valois has invented the "flashage", a cure for depressed people. After having tested it on monkeys, he tries with a first human patient, Alain Durieux. This is great success, everybody's happy except may be Alain's wife, Jeanne, who's worrying about the changes in Alain's personality. Other patients use the treatment with similar successes, and Valois's happy about it. But the monkeys are changing: non-cured ones are made mad by the over-stability and stereotyped behaviour of the cured ones. So are the humans. When Valois realises he can't stop the process, he decides to "flash" himself.