La parole est au témoin: Mustapha, a cab driver in Paris, charges a customer in a hurry, without realizing that he is in a hurry to escape his pursuers after robbing a jewelry store. The next day, reading the newspapers, Mustapha becomes aware of the role he has played in this affair, and would gladly assist the police if a fortuitous incident didn't make him fear the criminals' vengeance. It's a cruel dilemma in which he is both suspected by some and threatened by others. Weak but honest, he manages to get out of this predicament at the risk of his life!