Word has it that Lou is a precocious child. She is thirteen years old, two classes ahead of everyone else, and has a tiny body that takes its time. She has a mother dazed by tranquilizers, few friends, and the heightened perception of a world askew. Lou must write an essay about a young, homeless woman. She has seen one at Gare d'Austerlitz in Paris. One who begs, asks for cigarettes, and falls asleep on the café table when Lou offers her a drink in exchange for an interview.
She is 18 years old, called No, Nora in fact, but everyone calls her No, and very soon Lou cannot get by without her. But No is unpredictable; she has grown up in state homes and is totally unlike anyone else. One day, she disappears. Lou tries to find her, convinced that they both need one another.
When No reappears in an exhausted, wretched state, Lou knows what she must do: No will come and live at her place.