Demons  (1985)

Theatrical Release Information:
Demons

Italian horror auteur Dario Argento produced and co-wrote (with director Lamberto Bava) this gory, nightmarish horror film set almost entirely within the "Metropol," a huge, cathedral-like Berlin cinema showing an invitation-only screening of a rather lame slasher film. The difference, of course, is that the cheap scares on the Metropol's screen are child's play compared to the horrors which soon emerge to lay hold of the unsuspecting filmgoers: when a young woman is scratched by part of a display in the theatre lobby, she begins to mutate into a fanged, slavering creature who then attacks other audience members, spreading the demonic infection until only a handful of survivors are forced to combat rampaging armies of inhuman beasts, making the latter portion of the film resemble Night of the Living Dead. A handful of sequels followed; there's a little "reward" for those who stick around for the end credits. ~ Cavett Binion, All Movie Guide