Ten years old Betty is afraid of ghosts and dark corners. When her sister Agnès leaves to go to high school, Betty is left by herself, between her parents - in the middle of a marriage crisis - and Rose, the almost dumb maid. That’s when Yvon steps over the wall between the garden of the family house and the nearby asylum. Moved by his frailness, Betty hides Yvon for several days inside the cottage where the bicycles are stored. Betty tells him her fears and joys and slowly Yvon becomes her best friend and confidant, even though Yvon doesn’t speak much. But the hiding place is not safe and Yvon is afraid to leave on his own, so Betty decides to run away with him…