Toward the beginning of "Supergirl," Zaltar (Peter O'Toole) is whisked off to the Phantom Zone. "Your suffering will be short," he announces dramatically. "Mine will last forever." Well, what did he expect? That's what he gets for losing the Omegahedron. And if he doesn't watch out, he'll get zapped with the Burundi Wand, the Salirian Fireballs or the Krypton Vortex.

There hasn't been anything this deliciously campy since "Star Trek II"; like that movie, "Supergirl" immerses you in a world of bizarre jargon and strange artifacts that its characters regard with droll aplomb. When Zaltar loses the Omegahedron, a sort of mystical power cell, he threatens the survival of his people. So one of them, Supergirl (newcomer Helen Slater), warps to Earth to retrieve it. Alas, the device has plopped into a bowl of salad dressing belonging to the picnicking Selena (Faye Dunaway), a practicing witch who, bellowing "Sikkarah fa skoo!" employs its powers for evil.

Along with her sidekicks, Bianca (Brenda Vaccaro) and Nigel (Peter Cook), Selena has always believed you can control people with arcane incantations and spider's broth; when the Omegahedron transforms these notions into reality, nobody's surprised. Selena lights Nigel's cigarette with the tip of her finger, and he replies disdainfully, "I have in my time seen a great number of things more impressive than a human cigarette lighter." And when a snap of her fingers imprisons him in a steel-barred sphere hanging from the ceiling, he comments, "Oh terrific -- the old dangling in the cage routine."

"Supergirl" is a nutty confection mixing the supernatural and the mundane. In order to blend in on Earth, Supergirl enrolls in a girls' school under the name Linda Lee; the math teacher, of course, is Nigel. And Bianca laments that "the only way we're gonna pay the bills is to do what I said and start our own coven." Linda is Clark Kent's cousin, and she rooms with Lucy Lane, Lois Lane's kid sister; screenwriter David Odell has a lot of fun with the coincidences.

Director Jeannot Szwarc could have done more with the action scenes, but he has a snappy sense of pace and comic timing; cinematographer Alan Hume contributes some beautiful photography, particularly in the aerial sequences; the special effects, by Derek Meddings and Roy Field, are first-rate, particularly a distorted fun-house-mirror shot when Supergirl is trapped in the maw of an angry beast.

Blond, blue-eyed Slater brings an engaging sweetness to Supergirl; and she plays Linda with an awkward, gawky girlishness, subtly different from her Supergirl role. Dunaway lacks the verve you need to deliver lines like "I am considering nothing less than world domination" -- she's too classy an actress for such broad fun. But Peter O'Toole brings an appropriate extravagance to Zaltar (from the kingly way he draws "venture" out to "venchoowah," he seems to be satirizing his own "Becket"). And Peter Cook plays the warlock Nigel as a bitchy hairdresser.

Movies like "Supergirl" succeed when they have fun with their material, rather than making fun of it. As this gaggle of old maids competes with Supergirl for the heart of the hunky Ethan (Hart Bochner, who has just enough Warren Beatty in him to be attractive), you realize where you've seen this before -- it's "Cinderella" with a kick.

"Supergirl," rated PG, opens today at area theaters.