The evil power of money, the dishonesty of so-called honest people, a false evidence and mere lack of luck lead Yvon -a young delivery man- to take part in a bank robbery. He is arrested but doesn’t even try to defend himself. As soon as he gets into jail, he lets himself into complete submission to authorities. But his cellmates’ cruelty and the prison head’s total incomprehension influence Yvon’s violent temper. Moreover, his wife lets him down and their only child dies after a disease. So, when he is free again, Yvon is taken by a furious desire to kill.The little old woman who is to be his last victim offers him shelter in a house she shares with her family, far from any other dwelling, on the outskirts of Paris. The woman knows it’s risky, but still helps Yvon out of pure generosity. For days on, Yvon witnesses her hard, unrewarding work for people who don’t have any respect for her and treat her very badly. Yet, she never complains.Yvon is somehow fascinated. One might think he will spare the old woman’s life. But he kills her and the relatives savagely only to steal a very small sum of money. On the very same night, Yvon is full of remorse and gives himself in to the police, who had already surrounded the house.