‘Poison Ivy’ (R)

Cooper, the narrator of "Poison Ivy," is a poor little rich girl. Played by Sara Gilbert, she's a mess of a thing without a friend to her name, living in Los Angeles with her beautiful mother (Cheryl Ladd), who's dying of emphysema, and her wealthy father (Tom Skerritt), who's going through a midlife crisis.

If she could, Cooper would rebel against her empty suburban life, but about all that she can manage is self-pitying sarcasm. In her heart, she'd love to be like Ivy (Drew Barrymore), whose slutty, "up yours!" attitude she has long admired from afar. Ivy, as it turns out, is just as much a loner as Cooper, and once they meet they instantly become best friends. Initially, the relationship runs smoothly. Ivy's self-reliance and sexy confidence helps draw Cooper out of her shell, and Cooper gives Ivy class. And director Katt Shea (who wrote the script with the film's producer, Andy Ruben) shows a genuine sensitivity to the volatility of the chemistry between them. This fragile, symbiotic friendship between the two girls is the best part of the movie; it's also the purest part, and the only place where the film is driven more by the fresh spirit of its characters than by its hand-me-down thriller plot. The problems in the relationship -- and in the movie -- begin when Ivy moves out of her aunt's house and in with Cooper's family. The product of a lower-class upbringing, Ivy revels in the upper-class creature comforts that Cooper takes for granted. And even if the family is dysfunctional, it's still an improvement over hers.

All is not quite right with Ivy, though. There's something creepy about her, especially in how she charms her way into the mother's good graces and the effortless, masterly way she spins the web of a lie.

Soon, it's clear Ivy is completely amoral, perhaps even psychotic, and that her goal is not merely to be the daughter the mother never had, but to become the mother, right down to her clothes, her car and her husband. But as the transformation evolves, the movie becomes more predictable and less interesting. Even though both Barrymore and Gilbert give solid, deeply felt performances, the characters begin to lose their individuality, becoming pawns in the filmmakers' thriller strategy.

Barrymore's role is the flashier of the two, and her cupcake looks give an innocence to Ivy's desperate seductions. She's grown into a very sexy, very interesting young actress. Gilbert, too, shows a marvelous subtlety, especially in capturing the rawness of Cooper's feelings. She's perfect at displaying the bitterness and paranoia -- the sense that everyone is out to get her -- that teenagers often feel.

As Cooper's Percodan-gulping mother, Ladd doesn't have much screen time, but she makes this melancholy faded beauty seem almost ghostly in her suffering. It's a delicate, surprisingly moving performance. But for the most part the actors' work seems incomplete because their characters are cut off before they can fully blossom. It's as if Shea didn't trust her own strengths enough to allow them to carry the movie. In giving in to the cheap thrills of the psycho genre, she's trashed the very qualities that initially made her work so impressive.

"Poison Ivy" is rated R for sensuality.