Director Darren Aronofsky finds comfort in telling cautionary tales, and “Black Swan” is his most foreboding one yet.

The film takes place in the competitive world of New York City ballet where constant pressure takes its toll on one company’s nimble dancers. Nina Sayers, played by Natalie Portman in an Oscar-worthy turn, is a prime example of what extreme pressure does to one’s psyche. Sayers is an eager yet self-deprecating talent who unravels when given the lead role in a modern retelling of “Swan Lake.”

A film is only as good as the sum of its parts, and “Black Swan” is built from quality ingredients. The screenplay perfectly weaves together elements of self-worth, sexuality and addiction. Best categorized as a psychological thriller, the film forces viewers to second-guess what they see up until the mind-numbing finish.

Portman’s performance will likely attain legendary status years from now. After a year of training to get in shape for the demanding dance sequences in “Black Swan,” she is so immersed in the role that the audience feels every crack in her psyche, especially Sayers’ amazing transformation from the White Swan to the Black Swan. Though childlike in the beginning of the movie, Sayers loses all of her innocence in frightening fashion by the end.

But film editor Andrew Weisblum is unable to establish a consistent pace for “Black Swan.” Most envision a ballerina as graceful, but his editing style is inundated with too many fast cuts and stylistic shots that seem wobbly and rhythm-free. Despite the intentional choppiness, it seems unneeded since viewers aren’t given a moment to catch their breaths and reflect on the action. Though the film focuses heavily on Portman — seeming one-dimensional at times — Weisblum nicely mixes up Sayers’ fantastical thoughts with her real ones. Without Portman’s strong presence, the audience could’ve been lost in the plot.

Aronofsky redeems consistency with stylistic trends similar to previous movies, particularly “Requiem for a Dream.” In both films, he sets the action in a city but creates isolation among the characters. And Matthew Libatique’s glamorous yet horrifying cinematography adds to the visual impact. With shots tightly framed on Portman, each rise on her toes shoots pain down viewers’ necks. The lighting sets the tone for the film’s succumbing darkness, changing from bright and hopeful to cold and desolate.

Though some actors don’t get the screen time they deserve, two performances are particularly noteworthy. “That 70s Show” star Mila Kunis plays Lily, a sly, rambunctious dancer who initiates a high stakes game of cat and mouse with Sayers. Lily isn’t physically imposing, but her deviousness is enough to make Sayers watch her back. Winona Ryder also has a bit part as disgruntled dancer Beth Macintyre, but she maximizes her brief role well by taking on a maniacal, ice queen persona after old age forces her from the Swan Queen role.

While Aronofsky’s latest feature isn’t the year’s best film, it’s certainly worth watching. “Black Swan” has some chinks in its armor, notably the haphazard editing that attracts too much self-attention, but Portman’s near-perfect acting is the real reason why “Black Swan” takes flight.

“Black Swan” was written by Mark Heyman and Andres Heinz and directed by Darren Aronofsky.