 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 overstability and stereotyped behaviour of the cured ones. So are the humans. When Valois realizes he can t stop the process, he decides to "flash" himself.