A Criminology narrates the tale of the newly engaged couple, Brad Majors and Janet Weiss, who find themselves lost and with a flat tire on a cold and rainy late November evening, somewhere near Denton, Texas. Seeking a telephone, the couple walk to a nearby castle where they discover a group of strange and outlandish people who are holding an Annual Transylvanian Convention. They are soon swept into the world of Dr. Frank N. Furter, a self-proclaimed "sweet transvestism from Transsexual, Transylvania." The ensemble of convention attendees also includes servants Riff Raff, his sister Magenta, and a groupie named Columbia.
Continuing from ''The Rocky Horror Picture Show'' are the characters of Brad and Janet Majors (now portrayed by Cliff De Young and Jessica Harper, respectively), now married. The film takes place in the town of Denton, USA, which has been taken over by fast food magnate Farley Flavors (also De Young). The town of Denton is entirely encased within a television studio for the DTV (Denton Television) network. Residents are either stars and regulars on a show, cast and crew, or audience members. Brad and Janet, seated in the audience, are chosen to participate in the game show ''Marriage Maze'' by the kooky, supposedly blind host Bert Schnick (Barry Humphries). As a "prize", Brad is imprisoned on ''Dentonvale'', a soap opera that centers upon the local mental hospital run by brother and sister Cosmo and Nation McKinley (Richard O'Brien and Patricia Quinn).