A masked man is handing out movie tickets to a special screening in a reopened movie theatre in Berlin.
Cheryl (Natasha Hovey) and her friend go to theatre where several other people are coming to see the film. In the lobby there are several props from the film including a mask. A woman tries it on and scratches her face.
As the movie plays the woman goes to the bathroom where the scratch has infected her and turns her into a demon that causes her to attack people turning them into demons too.
Cheryl and some the other people try to fight the demons and escape the theatre. One demon does escape the theatre.
Mario Bava’s son Lamberto directed this with Dario Argento producing. The movie was successful enough that a sequel also directed by Bava was made.