On his 9th birthday, Camille reveals to his mother Ariane that he wants to return to his "real" home and his "real" mother. He leads her through the steets of Paris to a neighborhood he recognizes, to an apartment where he claims he lives. The owner, Isabella, is not there, but later it is revealed that she lost her own son only a few years ago. When Isabella returns, Camille refers to her as his mother and changes his name to Paul. Ariane grudgingly asks Isabella to come and live with them, hoping the child will soon tire of this double game. But he doesn't. Instead, he acts as if possessed. When friends decide to intervene and remove the second mother from the scene, trouble erupts.