A grenade robbery has been committed. It bears the trademark of Rock and yet it is in fact Tango, a professional poker gambler who is its author. Rock is furious and sets out to find the usurper. He picks up his track, abducts Alice, Tango's mistress, and, by means of threat, tries to oblige Tango to go on holding up banks for him. Tango refuses but, surprisingly, Rock does not insist. Maybe because he feels more and more attracted to Alice. The two men end up becoming friends. But police superintendent Luther, who is after Rock, is drawing closer...