Portrait of a two-faced man. By day he is rich, brilliant and respectable financial officer Lussac; at night, he becomes "Mirror", a ruthless gang leader in Marseilles.

Between eleven o’clock and midnight one evening, a notorious trafficker Jérôme Vidauban is shot whilst walking in a tunnel in Paris. The case is assigned to Inspector Carrel, who is Vidauban’s perfect double. Using his resemblance to the arch criminal, Carrel manages to infiltrate in Vidauban’s circle of acquaintances and contacts. He becomes embroiled in a bizarre web of intrigue and discovers no shortage of possible murder suspects, all of whom appear to be surprised to see him still alive.