Monsieur Prioux is completely bewildered. Until yesterday, he and his wife Laurence led a contented and peaceful life. Their tranquility comes to an abrupt end when a strange man named Patrick suddenly appears in the supermarket and seems to be lying in wait for them. Things get even stranger when Patrick claims to be their son. That can't be true—the Priouxs have no children! Is this absurd claim a cruel joke? Or is Patrick simply a cunning con artist? The Priouxs are baffled...