[1] The film concerns the police investigation of the murder of a cinema attendee who is shot dead during a matinée showing of a Spaghetti Western starring Giuliano Gemma.
Some audience members exhibit unusual behavior, such as the secret lovers in a back row or the man who uses the restroom for a suspiciously long time.
He can understand the suspicious behavior of some of them: For example, he learns that the two lovers are married to other people and have been meeting secretly in the movie theater.
In this reconstruction, a popular usher from the movie theater sits in the seat of the murdered man, and is also mysteriously shot at the end of the western.
Before the gunshot in the film takes place, he stands up and runs through the movie theater, filled with fear, because the gunslinger on the screen is looking directly at him and aiming his revolver at him.
In an interview conducted before his death in 2023, director Giuliano Montaldo cited that the Ray Bradbury short story The Veldt was a direct inspiration on the screenplay, though it was not ultimately an official adaptation.
Gemma recreated his character's appearance in new footage shot by Montaldo to make his film gunslinger sentient and aware of the audience.