When the Paris police's vice squad - on the orders of Police Chief Lépine - begin to clean prostitutes off the city's streets, a man's body is found in the Bois de Boulogne. Inspector Antoine Jouin is entrusted with the investigation.

Nenette, who has the mental age of an 8-year-old, has always lived with her mother, who raised her alone. Nenette works, cleaning the community school, and her best friend is a tortoise. But when her mum dies, she faces life in a retirement home. But, as the institution doesn't accept animals, Nenette sets out with her suitcase and her tortoise, planning to find her father, whom she knows only by a yellowed photograph, a letter and an address.