Antoine is five years old. Lucie, his older sister, has gone away. At least that's what his parents have told him. Now there is only his mother at home. All joy seems to have abandoned her. As to his father, he comes to see them now and then, but he never stays the night. So, left to his thoughts and memories, Antoine waits for Lucie, persuaded that he possesses the magical formula that will make her come back: a bit of luck, three oranges, and three elevators.