Mila Kunis joins Darren Aronofsky's "Black Swan" (2010) with Natalie Portman

Mila Kunis (Forgetting Sarah Marshall, Extract) has signed on to co-star oppositeNatalie Portman in Darren Aronofsky’s Black Swan.

The supernatural drama is set in the world of New York City Ballet. Portman stars as a veteran ballerina who finds herself “locked in to a competitive showdown with a rival dancer, with the stakes and twists increasing as the dancers approach a big performance.” But it isn’t as simple as that — the big twist is that Portman’s character is not sure whether her rival is a supernatural apparition or if she is having delusions. Kunis is playing the rival dancer named Lilly.