It's a summer holiday weekend in Paris and Antoine and Hélène are on their way to pick up their children at summer camp, thus joining thousands of other vacationers on the highways to the south of France. At first in high spirits, the couple starts sniping at each other during the drive as tensions in their relationship bubble to the surface. Frustrated by the freeway, Antoine takes a byway detour, much to Helene's displeasure, and then leaves her in the car as he stops for a drink. Once they're back on the road, their bickering escalates, with Antoine blaming Hélène for his drinking. Antoine then stops again to continue drinking at another tavern, although this time, Helene warns that she won't be there when he gets back. Still he defies her and goes into the bar, taking the car keys with him. He panics when he leaves the bar and discovers she has left. Believing that she has taken the train, he drives like a madman to the next station, but upon his arrival, the last train is mid-pulling out of the station. Driving away in a state of dread, he picks up a strange hitchhiker--not knowing he might have already crossed the path of his soon-to-be-missing wife.