A psychological drama that details the tormented relationship between Marie and her mother, stemming from Marie's childhood on their estate in Algeria. The mother, Eliane had lost a child before Marie was born and was consumed with hatred for her husband who was carrying tuberculosis and may have been the cause of the child's death. That hatred was never resolved, and Marie grew up in a bitter and strained household. As both women grow older, Marie marries and raises a family while her mother sinks ever deeper into anger, frustration, poverty, and isolated despair. She vents her destructive emotions on her daughter and is completely resistant to her daughter's attempts to help her, to make her life better.

During a robbery that goes wrong, Valentin Tralande kills his accomplices and bank customers.

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.