Michel Poiccard (Jean-Paul Belmondo) is a petty thief who makes money by stealing cars and driving them to Paris to resell. When during a job Michel is pulled over by a motorcycle policeman he shoots him dead and must find a way to escape the closing dragnet. In Paris Michel pilfers more money from an old girlfriend, and mugs a stranger in a rest room, and looks up American girl friend Patricia Franchini (Jean Seberg) an aspiring journalist who hawks the New York Herald Tribune on the Champs Elysees. Michel needs to collect money for his car but also emotionally is drawn to Patricia having slept with her previously and seeking some more stable bond but Patricia is apprehensive about their eventual success together. After Michel has collected his money and makes plans for him and Patricia to go away together, Patricia learns from the Police about Michels crime background and must make a heartfelt decision that may change their lives forever.