This one of a handful of Italian gialli that began life as a TV movie (the other two being "Secret of Seagull Island" and "Scorpion with Two Tails"). Like those, it lacks a lot of the sex, violence,and cinematic flourishes of other gialli, but it's a lot tighter (it wasn't condensed down from a mini-series like the other two), and it has a great plot: A large group of people are gathered in a cinema watching a spaghetti Western when one of them is found dead, killed by what by all accounts appears to be a "stray bullet". The police have to hold the increasingly restive crowd in the theater while they look into the victim's past to find out who may have killed him and why. . .
This movie has no really famous actors, but it does have an interesting cast. Flavio Buccio played a thug in both "The Night Train Murders" and Dario Argento's "Suspiria". He really plays against type here as a weird psychologist. Both William Berger and Guliano Gemma appear in the Western movie-within-a-movie. Berger was a pretty famous actor in the 60's and he is the father of both Debra ("Inglorious Bastards") Berger and Katya ("Absurd") Berger (but to my knowledge no relation to Helmut Berger). The teenage girl who first discovers the dead body is Elizabetta Virgili, later semi-famous in Italy as a nude centerfold and showgirl (she was in the erotic drama "Family Scandal" a few years later where she obviously showed a lot more than she does here). Although I don't know her name and I never saw her in anything else, my favorite though was the actress who played the old lady who becomes indignant that the police don't consider her a suspect and want to interrogate her.
Obviously, this is a pretty low-watt giallo, but it is an entertaining one.