Demons

• Dario Argento produced and co-wrote the script with Franco Ferrini; the story started life as a single segment of a horror anthology Dardano Sacchetti was developing before Lamberto Bava singled it out and expanded it to a feature.
• Shot in nine weeks across June and July 1985, splitting time between West Berlin and De Paolis In.Ci.R. Studios in Rome. The Metropol exterior is a real Berlin building, now the Goya nightclub, which has hosted horror conventions off the strength of its screen time here.
• Sergio Stivaletti built the makeup effects, the splitting fingernails, teeth shoving out through gums, and geysers of green pus. He'd come straight off Argento's Phenomena, kicking off a long run as Argento's go-to effects man.
• The demons' glowing eyes were a happy accident. Actors wore refractive paper in close-ups and the reflection on set produced the glow with no optical trickery added.
• Argento packed the soundtrack with heavy metal and rock instead of pure orchestral dread, Claudio Simonetti's score sharing space with Motley Crue, Billy Idol's White Wedding, Accept's Fast as a Shark, and Saxon.
• Released by Titanus on October 4, 1985, it grossed 1,225,490,000 lire, landing as the 39th highest-grossing Italian film of the year, Bava's biggest commercial hit. The intended third entry got rewritten into Michele Soavi's The Church (1989).

The film-within-a-film is the whole point: the movie on the Metropol screen predicts and triggers what happens in the seats, collapsing the wall between watching horror and living it. Demons reads as horror cinema turning on its own audience, the genre literally infecting the people who paid to be scared.

The lobby mask is the engine, not the projector. The curse only activates when a patron physically handles the prop, which frames the carnage as punishment for touching what should stay behind glass, the fan who reaches past the velvet rope and pays for it.

The Berlin setting and the bricked-up exits aren't incidental. The theater becomes a sealed city-within-a-city, and when the survivors finally claw out to find Berlin already overrun, the screening reads as ground zero for an apocalypse that was always going to escape the room, no safe outside to run to.

A masked man hands out free tickets to a screening at Berlin's Metropol, a cavernous theater with a prop motorcycle and a demon mask propped in the lobby. When a hooker tries the mask on for laughs and nicks her cheek, the cut festers, splits, and turns her into a clawed, pus-spraying thing. The infection rips through the trapped audience as the movie on screen mirrors their slaughter beat for beat. Survivors carve a path out with that lobby motorcycle and sword, only to find the whole city already gone.