After a group of young revolutionaries break into a corporation's headquarters and steal $5,000,000 worth of heroin to keep it off the street, they call on San Francisco Police Lieutenant Virgil Tibbs for assistance. Though sympathetic to their cause, the straight-arrow Tibbs refuses to consider it because they broke the law, but when the group is then accused of a murder it didn't commit, Tibbs finally joins them in order to ferret out the identity of the real killer, while keeping his now rogue undercover investigation a secret from his SFPD superiors.