Hell hath no fury like a woman superhero scorned in director Ivan Reitman and screenwriter Don Payne's loopy cross-pollination of comic-book mythos and crazed-ex-lover melodrama. Luke Wilson is the on-the-rebound architect who falls for a bookish gallery curator (Uma Thurman), only to discover she's really the alter-ego of G-Girl, an indestructible, meteorite-enhanced crime fighter. G-Girl's a whiz-bang in the bedroom too; when she and Wilson make love -- a hilarious scene -- the earth literally moves under their feet. But romantic bliss is short-lived for these two lonely hearts, and when Wilson tries to break things off, G-Girl goes nutzoid. My Super Ex-Girlfriend is a one-joke movie, but the joke happens to be a good one -- a Tracy-and-Hepburn-style battle of the sexes in which Kate can fly and blast through walls -- and Reitman (who made Ghostbusters) feels at home with the mix of screwball and supernatural. A talented supporting cast (Anna Faris, Wanda Sykes, Eddie Izzard) flounder in underwritten roles, while Thurman gets her best comic opportunities since The Truth About Cats & Dogs: She's an inspired goofball, switching personalities and wardrobes with the quick-change precision of Christopher Reeve in his prime.