Stop! is a 1970 American independent drama film that was once considered a lost film. It was written and directed by Bill Gunn. It stars Edward Michael Bell, Linda Marsh, Richard Dow, Marlene Clark, John Hoffmeister, and Anna Marie Aries.
Michael and Lee are a married couple whose relationship is in turmoil. While on vacation in San Juan, Puerto Rico, they meet another couple (Richard and Marlene). Gradually, they become a foursome, mingling with group sex, as well as separate heterosexual and homosexual encounters.
Warner Bros. refused to release the X-rated film theatrically. It was eventually shown periodically from 1970 onward, albeit without a proper release. Its only existing copy is a grainy VHS rip.