Léon, the top hit man in New York, has earned a rep as an effective "cleaner". But when his next-door neighbors are wiped out by a loose-cannon DEA agent, he becomes the unwilling custodian of 12-year-old Mathilda. Before long, Mathilda's thoughts turn to revenge, and she considers following in Léon's footsteps.

Urban horticulturalist Brontë Mitchell has her eye on a gorgeous apartment, but the building's board will rent it only to a married couple. Georges Fauré, a waiter from France whose visa is expiring, needs to marry an American woman to stay in the country. Their marriage of convenience turns into a burden when they must live together to allay the suspicions of the immigration service, as the polar opposites grate on each other's nerves.