Opening Friday, “Black Swan” is so haunting, so engrossing, you might be tempted to invest it with more meaning than it warrants. With its über-creepy shock effects, swirling camerawork and Oscar-caliber performance by Natalie Portman (“Brothers”), the psychological thriller directed by Darren Aronofsky (“The Wrestler”) is a ballet/showbiz picture awash in LSD. It’s trashiness masquerading as high art. Which is to say, it’s pretty damned irresistible.

Not that the viewer has much choice in the matter. Aronofsky prods the audience into the discomfiting point of view of Nina Sayers (Portman), a gifted New York City ballerina whose grip on reality is pas de dubious.

An ambitious perfectionist, she is cast as the Swan Queen in an edgy version of “Swan Lake” being staged by megalomaniacal artistic director Thomas Leroy (Vincent Cassel, “Eastern Promises”). Nina’s technical proficiency makes her a natural fit for the ballet’s White Swan, but she lacks the spontaneity needed to portray the second half of the dual role, that of the walk-on-the-wild-side Black Swan.

Still, Thomas hopes his newly christened Swan Queen will explore her sexuality for the Black Swan, and he uses some unorthodox methods to coax Nina along. But the woman’s inner journey is more nightmare than awakening. At home, she’s at the mercy of an overbearing mother (Barbara Hershey, “Riding the Bullet”) who appears to believe her daughter is still a child. At work, Nina is rattled deeply by the sudden arrival of Lily (Mila Kunis, “The Book of Eli”), a new dancer from San Francisco who quickly becomes her rival. Lily, a sexually charged free spirit, is everything that Nina is not.

And so begins the primary dance of “Black Swan,” an is-it-real-or-isit-madness pirouette that finds Nina whirling ever closer to the abyss.

Aronofsky’s past efforts, including 2000’s “Requiem for a Dream” and his audacious 1998 debut, “ ,” were chock full of thematic ambition to spare. By contrast, “Black Swan” is the sort of Grand Guignol horror show that Roman Polanski and Brian De Palma conjured up back in the day. Nina’s perfectionism and bottled-up sexuality begin to fracture — a momentary hallucination here and there — before erupting in a phantasmagoria of sex and violence, with the film serving up ample portions of both.

Portman’s smarts and beauty have made her a fanboy fave for years, but rarely has she had a platform to demonstrate her acting chops. “Black Swan” provides that opportunity, and she makes the most of it. In a role that must have been as physically demanding as it was emotionally exhausting, Portman slides down the rabbit hole with true conviction. She leaves the rest of her capable cast in the dust, although Winona Ryder (“Star Trek”) is memorable as an aging ballerina, while Hershey resonates as the malice-filled mama.

The most fine-tuned performance, however, comes from Aronofsky’s behind-thelens choreography. Through a meticulously constructed narrative, he seduces his audience into identifying closely with the increasingly insane Nina Sayers. For a nightmare, it curiously turns out not to be such a bad place — at least not for an hour and a half.