Paris, at the end of the fifties. Paul Dumery, former insurance salesman approaching his forties, wouldn’t stand out in a crowd. He scrapes by from day to day, coping as best he can with his desperate financial situation. On the brink of ruin, he accepts to meet Sarreby, a money-lender and loan shark, a pal of his friend Daubelle. The day before his meeting, Paul’s imagination runs riots. He sets himself a challenge: to go to Sarreby’s office with a hammer in his pocket. He’s never stolen a thing, so there’s no danger that he’ll commit a crime. However, the next day, he fatally wounds the awful crook and steals 70,000 francs from him. Paul is now a murderer on the run.