The Umbrella Coup

The Umbrella Coup French Le Coup du parapluie is a 1980 French comedy film directed by Grard Oury, starring Pierre Richard, Gordon Mitchell and Gert Frbe.

The unsuccessful actor Grgoire Lecomte is heading for a casting but then he takes a wrong turn. While he thinks he talks to casting director who wants an actor to play a henchman, he actually talks to a mafia don who wants a real killer. Lecomtes performance is convincing and consequently he receives a contract to finish off arms dealer Otto Krampe. He is supposed to kill Krampe with an umbrella containing a builtin syringe full of potassium cyanide at his birthday party in StTropez. Lecomte takes the don for a producer and believes this was all part of shooting a film.

Source: Wikipedia