At midnight, they flock to an old art deco movie palace in the Detroit suburbs.

A glow-in-the-dark dragon mural lights up one of the screening rooms at the State-Wayne Theater in Wayne, Mich. There, twice a month, the Michigan Rocky Horror Preservation Society holds court, its members arrayed in corsets, feather boas, ripped jeans and lovingly detailed costumes that evoke their favorite movie’s main characters.

The Rocky Horror Picture Show turns 50 this year, with scores of groups around the world keeping its legacy alive, including this one in Michigan.

“We are the original immersive 3D movie experience,” says Becky Milanio Koupparis, the chief operating officer and director emeritus. She first dressed up in goth glam to attend a screening at age 16, in Berkeley, Calif. That was 44 years ago. Now she’s a well-known member of the national community.

Koupparis, who makes costuming a speciality, is among the most senior members of this group, which first numbered about 15 people when it was founded in 2013. Now about 60 hardcore volunteers loyally attend screenings as “phantoms,” who enthusiastically call out responses to what’s happening on screen and throw toast when an on-screen dinner toast is proposed. Others act out the movie underneath the screen as it plays, as the “shadowcast.”

“We are trying to mimic every single small movement: lip-synch, turn, dance move, every single thing that they’re doing,” explains Moonbeam Albin-Frey, a founding member of the group.