On the way to visit an old college professor, the two clean cut kids, Brad Majors (Barry Bostwick) and his fiancee Janet Weiss (Susan Sarandon), run into tire trouble and seek help at the site of a light down the road. It's coming from the Frankenstein place,' where Dr. Frank N Furter (Tim Curry), a transvestite from the planet Transexual in the galaxy of Transylvania, is in the midst of one of his maniacal experiments - he's created the perfect man a rippling piece of beefcake christened Rocky Horror (Peter Hinwood), and intends to put him to good use (his Own) in his kinky household retinue, presided over by a hunchback henchman named Riff Raff (Richard O'Brien) and his incestuous sister Magenta (Patricia Quinn), and assisted by a tap dancing groupie-in-residence, Columbia (Little Nell).
Agape in this world of science fiction and fantasy, Brad and Janet don't know what next to expect, till the disastrous result of Frank N Furter's previous experiment, an oafish biker unwed Eddie (Meatloaf), plows through the laboratory wall, wailing on a saxophone. Frank puts a permanent end to this musical interruption without thinking twice until the old professor Brad and Janet had set out to visit, Dr. Scott (Jonathan Adams), turns up at the castle in search of his missing nephew, the juvenile delinquent Eddie. He knows that Frank N Furter is an alien spy form another galaxy, and sets out to turn him in, but Frank moves too fast, seducing first Janet, then Brad into his lascivious clutches. Overwhelmed by a newfound libido, Janet hotly attacks the stud Rocky Horror while Brad is under the covers with Frank.
Before Dr. Scott can bring justice and morality into this topsy-turvy Transylvanian orgy, Frank N Furter has turned his captives to stone, in preparation for a new 'experiment' - an all drag revue - when Riff Raff and Magenta reappear in Transylvanian space togs to wrest control of the mission from Frank N Furter, whose lifestyle is too extreme even for his fellow space travelers. When his lavish histrionic claims of chauvanisrn fail to soften up Riff Raff and Magenta, Frank N Furter tries to escape, only to be gunned down by their power rayguns. Rock rushes to save his creator, but he, too, is blasted to outer Space by the militants.
Brad, Janet and Dr. Scott are left in a fog, incapable of readjusting to the normalcy of the life they've left behind in Denton, now that they've tasted the forbidden fruits of the Time Warp.