A giant alien brain possesses a young nuclear scientist. A rival alien possesses the scientists’ dog and conflict ensues.

For the 300 B-Fest participants, there’s 22 hours to go.

Starting at 6 p.m. Friday, students and fans from all over the country subjected themselves to 24 hours of bad movies. Participants brought pillows and bags of snacks to McCormick Auditorium at Norris University Center for arguably the weirdest sleepover on campus.

B-Fest began in 1981 as a marathon of B-movies where audience members heckle and come on stage to imitate the films. People roll tires across the stage after car crashes, toss paper plates when they see flying saucers. They shout, they chant, they cheer.

Many of the films are old, low-budget monster movies. Some strive for deeper meaning. In “The Forbidden Dance” a Brazilian native princess fights to protect her home in the rain forest by coming to America and winning a dance contest. “Robot Jox” was a post-apocalyptic retelling of the Iliad — with Achilles, Athena and Alexander all doing battle in giant robots.

This year’s lineup also included a 1970s pornographic version of “Alice in Wonderland” where a shy, innocent girl journeys to Wonderland to learn about sexuality. When the lead actress also appeared as Jackie Chan’s love interest in “The Big Brawl” audience members screamed, “It’s Alice! We’ve seen you naked.”

The highlight of the festival came at midnight. B-Fest veterans and confused first-timers rushed the stage for “The Wizard of Speed and Time.” People lay on their backs and “ran” as the film’s title character zipped through changing landscapes, stomping their feet in time with his song at the end. Traditionally the film short then is repeated backwards and sometimes upside-down.

The audience then cleared the stage and returned to their seats for “Plan 9 from Outer Space,” the festival’s most-aired film. An entire set of traditions have developed around it including screaming “Day” and “Night” depending on the shot, because poor editing often shows the time changing mid-scene.

Though viewers often break from movie -watching to take naps, talk or play cards, people still feel the exhaustion of the movie marathon.

The feeling was summed up in a comment during one scene where a nearly comatose prisoner is returned to his cellmates after brutal mental torture.

“Hey guys,” shouted Rodrigo Lopez, a Communication junior. “I just watched 24 hours of B-movies.”