Lamberto Bava, son of Italian horror-maestro Mario Bava, directs this tale of a bunch of cinemagoers with invitations to a special film show. The film in question is a gruesome slasher flick, and as the screening progresses members of the audience begin inexplicably transforming into hideous blood-thirsty demons. The rest of the audience tries to escape, only to discover that all the exits have been walled shut....