Jef Costello is an assassin. A smart, experienced and cold-blooded professional who is considered the best in his field. During the execution of the next order, he accidentally encounters an undesirable witness — a nightclub pianist who saw his face. The police commissioner organizes a hunt for the killer, and Jeff, along with the rest of the suspects, is taken to the station for identification and interrogation. But thanks to a well-organized alibi and the testimony of a pianist who "did not recognize" Costello, he is released. Concerned about this development, the customers decide to take the Boss out of the game, but everything is not going according to plan.