Innocent Assassins(1973)

Original title: Ártatlan gyilkosok

Two arts students, András and Viktor who are writing their thesis on detective stories, make up a story and keep nagging the famous film-director, who just came back from Hollywood, until he undertakes the job. At night they work on the film, in which two youths kill a director returning from the US. In the morning the director is found dead - a knife in his back.