Directed by Édouard Molinaro and co-starring Lino Ventura, Caroline Cellier, and Jean-Pierre Darras, L'emmerdeur is an adaptation of Francis Veber's 1971 play Le contrat.

Ralph Milan is a contract killer who is paid to kill Louis Randoni, whose testimony in various trials could harm the organisation.

Ralph waits for his prey in his hotel room, but is interrupted by his comical neighbour, a shirt salesman named François Pignon (Jacques Brel).

Pignon, who is suicidal since his wife left him for a reputed psychiatrist named Fuchs (Jean-Pierre Darras), tries to hang himself on the waterpipes, but only manages to cause a flood.

Realizing that if Pignon tries to kill himself again, the police will search the place, Milan offers to talk him out of it until after his assassination.