Nina wakes up looking happy and tells her mom, Erica, that she had a dream where she was dancing as the white swan. As this is such a big deal for Nina, who is a ballerina, her mom also shares in the excitement.
During breakfast, Erica can’t help but notice how Nina is in such a good mood. When she mentions it, Nina says her ballet director, Thomas, has informed her that he’ll feature her more in the coming shows. Her mother looks happy to hear this, and she says Nina deserves it because she is the most dedicated dancer in the company.
After they’re through with her meal, Erica notices a rash on Nina’s back when she’s about to help her wear her shirt. Nina says it’s nothing, but Erica doesn’t look like she believes her daughter.
Nina, however, heads out to the theater, and when she gets there, a group of girls are talking about how an experienced ballerina named Beth, is about to be dropped by Thomas. Beth is now getting old, and Thomas is thinking about replacing her with someone younger who can play the main character in an upcoming show for Swan Lake.
Nina initially remains silent as the other girls talk, but she soon defends Beth, saying she’s still a good dancer. However, the other girls don’t share the same thoughts. Shortly after, a new girl named Lily comes in, and the other girls in the room, including Nina, can’t help but stare at her.
Later that day, during practice, Thomas walks in and starts talking about how he needs a younger dancer who can play both the white and black swan, as part of his Swan Lake show. He taps a few girls and then tells them that those he didn’t tap will audition for the role.
Nina is among those who didn’t get tapped, so she looks relieved that she can still get the role. After practice, Nina sees Beth angrily scattering her room and throwing things around.
Beth doesn’t look happy as she has been informed that she will no longer dance as part of Swan Lake. She walks out of the scattered room, and Nina can’t help but go in. She sees some of Beth’s things and picks them up, as she plans to be the new Beth.
When it’s time for the audition, Thomas is impressed with Nina’s performance, but he lets her know that she would only get the role if he was casting for just the white swan. As her black swan act still needs some work, Thomas asks her to keep dancing.
Suddenly, Nina gets distracted and loses her balance when Lily barges in. With that, Thomas believes he has seen enough for the day, and he tells her they’ll continue the next day.
Nina is not happy with how she performed, and when she gets home, she cries in Erica’s arms. Because she knows that she needs to be perfect to land the role, Nina continues practicing at home.
However, she pushes herself too hard and ends up injuring her toe. Erica helps Nina take care of the wound that night, and while they’re talking, she tells Nina to stop trying too hard. But Nina doesn’t seem to care as she really wants the role, and also plans to tell Thomas that she has perfected the dance, even though she got injured and didn’t complete it.
Erica again tells her not to do that, because it will not convince Thomas to give her the role. She also tells Nina that even though there’s pressure on her to land the role because she’s also getting old, she doesn’t have to let it get the better of her.
The next day, Nina goes to Thomas’ office to tell him she has perfected her dance. Thomas doesn’t sound impressed, as he says she needs to loosen up if she wants to get the role. He says that while she’s the perfect person for the role of the White Swan, she’ll need to be less rigid to do a good job as the Black Swan.
Nina is nearly drawn to tears as she doesn’t think she’ll land the role. Thomas asks her to leave the office because he has chosen another lady named Veronica, but as she approaches the door, he stops her and tells her that he expects her to convince him that she deserves the role.
He goes on to talk about how she needs to stop being obsessed with getting everything perfect, as it can hinder her ability to take up the role. Suddenly, he tries to make a move at her, and she rejects, after which she leaves.
Later that day, a group of girls start talking about how the list for the Swan Lake casting is out. Knowing that it’s already going to a girl named Veronica, Nina congratulates her and decides to leave the building.
However, Veronica checks the list and quickly runs to meet Nina to accuse her of trying to mess with her. Nina doesn’t understand this, but from how angry Veronica is, she realizes that someone else has been picked.
With that, Nina goes to the board and sees her name in the role of Swan Queen. Immediately, she runs to the bathroom and calls her mom to share the good news while crying.
That night, when Nina gets home, Erica is not around yet, so she goes to freshen up in the bathroom. While she’s there, she notices that the rash on her back is now worse, and as she tries to clean it, her mom arrives. Nina quickly cleans up, as she doesn’t want her mom to see the rash again.
When Nina leaves the bathroom, she goes to see Erica, who has brought home a cake for them to celebrate. She cuts a portion for Nina, who starts complaining that it’s too much.
Erica is unhappy with this, and she decides to throw away the cake if Nina wouldn’t appreciate it and let them celebrate. Nina changes her mind and begs Erica not to throw it away just to please her mother.
The next day, intense practice starts for the Swan Queen. Thomas looks impressed again with Nina’s performance as the White Swan, but he says her Black Swan performance is still below par. He says she should be trying to capture the audience, but she’s falling short of what is required because she’s not loosening herself.
Later that day, Nina watches Lily dancing, and Thomas tells her to emulate Lily, who just seems to be enjoying herself rather than being too bothered about whether she’s perfect or not. Shortly after, Nina is taken to her new changing room as the Swan Queen.
That night, Thomas introduces Nina to a group of sponsors who he is inviting to watch his next show, which has her as his main character. As part of his speech, he calls Beth his little princess and says that she’s retiring.
Beth doesn’t seem to be happy with the speech, as it doesn’t exactly point out that she’s being forced out. As a result, she walks out, leaving the guests wondering what the problem is. However, Thomas is able to change the topic and get some applause for Nina.
Later on, when Nina is using the restroom, she is hurried by someone who is knocking repeatedly. It turns out to be Lily, who looks happy to see Nina, and also congratulates her on bagging the big role. Lily wants to continue having a conversation with Nina, but Nina is not in the mood, so she just leaves.
After the event, Thomas asks Nina to wait for him, so she can follow him to his apartment for further discussions on the role. Before they can leave, one of the sponsors of the show needs to see him, so he asks Nina to wait. While she’s waiting, Beth shows up and starts blaming Nina for taking her role.
She accuses Nina of bribing Thomas to get the role, but Nina defends herself. Shortly after, Thomas shows up and tells Beth to go home while he takes Nina to his apartment. When they get there, Thomas tells Nina that he knows it’s not easy for Beth to accept her retirement, but he wants Nina to take up the role very well.
He also says they need to get to know each other very well, though he ends up asking some really uncomfortable questions. When he sees that Nina doesn’t respond as well as he wants, he tells her to go home and rest so that she can be ready for practice the next day.
When Nina gets home, Erica asks her about her day as she helps Nina take off her clothes. However, her attention is drawn to the rash on Nina’s back, and Erica is furious, saying that Nina has started scratching herself again. It appears that Nina has a scratching problem, and Erica has to force her into the bathroom to cut her nails off for her.
On the next day during practice, Nina is dancing when a lady walks in and announces that Beth got into an accident. Nina goes to see Thomas after practice, and Thomas says Beth always had a dark impulse that he knew would eventually get her to do something wild, even though he acknowledges that it’s what makes her so good at her performance.
When Nina asks if Beth’s accident was immediately after they spoke to her the other night, Thomas tells her not to worry about it or let herself get distracted by it. But this doesn’t stop Nina from going to see Beth in the hospital.
Beth is still in a coma when Nina gets there, and she brings some flowers along with her. Before she leaves, Nina sees how bad the injury to Beth’s leg is, and she can’t help but be scared for herself.
The next day, Thomas continues to complain about how Nina is being too stiff. He keeps shaking his head as he watches her, and soon after, he tells her partner to leave so that he can train her personally. As they’re training, Nina still doesn’t get it, and Thomas leaves, complaining that Nina still doesn’t know how to make her performance well.
Nina feels overwhelmed and starts crying when Thomas leaves. While she’s at it, Lily sees her and tries to comfort her with some kind words. Nina appreciates it, but when Lily starts to imply that Thomas is being too hard on her, Nina defends him and walks out.
On the next day, Thomas starts to push Nina really hard, but she doesn’t understand it. She, however, realizes that Lily had spoken to Thomas about how she saw Nina crying. She also told Thomas to take things easy with Nina.
Thomas doesn’t appreciate this as he talks to Nina, who apologizes for what happened. When she’s through, she goes to find Lily and blames her for trying to make things hard for her.
Lily pleads her innocence, saying she only bumped into Thomas and couldn’t help but mention it. Nina tells Lily she doesn’t like it and she should mind her business.
At home, Erica sees how anxious Nina feels as she’s trying to clean her shoes, and she asks if Thomas is pushing her too hard or trying to take advantage of her.
Nina says nothing like that has happened, and she seems to be tired of her mother poking into her business. Erica says she’s only trying to keep Nina from making the same mistake that led to her sacrificing her career to give birth to her.
Nina tries not to respond, but when her mother asks to see her rash to make sure she’s no longer scratching it, she blatantly refuses. Just then, the doorbell rings, and Erica goes to answer it.
It appears to be that someone is there to see Nina, but Erica says Nina is not around. Nina doesn’t like this, and she goes to check who it is. It happens to be Lily, who says she only came to say sorry for what happened between her and Thomas.
Lily also offers to take Nina out to dinner. Nina hesitates at first, but when Erica seems to start calling for her to come inside, Nina decides to go with Lily, much to Erica’s dissatisfaction.
At the bar, they start talking about the dance. Lily also talks about Thomas and says she finds it weird that he calls Beth his little princess. Nina doesn’t think it’s a problem, and Lily jokingly says that Thomas would start calling her like that soon enough.
Not long after, Lily offers to spike Nina’s drink with a drug so that they can both get high. Nina doesn’t want this, so she rejects the offer. However, when she goes to the restroom and returns, Lily convinces her to take it. Nina agrees, and both of them start chatting with two guys who seem to be very interested in them.
After that, they head out. Lily follows Nina home, and as they enter the house, Erica can’t believe that Nina is drunk. She tries to caution her, but Nina runs to her room and blocks Erica from coming in.
The next morning, Nina wakes up very late and doesn’t see Lily around. On her way out of the house, she blames Erica for not waking her up. When Nina arrives for practice, it’s already late, and Thomas has already begun the training with Lily.
Nina is asked to warm up, but after Lily is through with her session, she explains that Thomas only asked her to do it before Nina arrived, and she’s not interested in taking the role.
Meanwhile, Nina laments about how Lily left her house without waking her up first. Lily doesn’t seem to understand this as she says she went home with one of the guys from the club while Nina went home alone.
It turns out that Nina had only been hallucinating, and Lily didn’t really follow her home on the previous night.
That night, Nina suddenly gets tired of the little princess’ treatment she has always received from her mother. As a result, she breaks her music box and throws out all the dolls in her room.
During practice the next day, Nina does quite well and impresses Thomas completely for the first time. While taking measurements for the dress she’ll wear for the show, Nina hallucinates and sees herself scratching her back in the mirror.
She looks shocked and wonders what happened, then sees Lily also ready to take measurements. Nina asks what she’s doing there, and Lily says Thomas made her alternate for Nina.
Nina immediately runs to find Thomas, and tells him to make someone else her alternate, as she thinks Lily is very interested in her role. Thomas says every dancer always has an alternate, and Lily is a good option.
He, however, tells Nina not to worry about her role, because she made a breakthrough in the last practice, and she only needs to do that one more time to clinch the role.
That night, Nina doesn’t go home until the pianist leaves her, and the lights also get turned off. The pressure seems to start getting to Nina, and she feels very anxious as she leaves.
Nina doesn’t go home directly, as she first goes to return the things, she took from Beth’s room to her in the hospital. When she gets there, Beth is sleeping in a wheelchair, but as Nina drops everything and is about to leave, Beth wakes up.
She asks Nina what she is doing, and Nina tells her she came to return the things she took earlier. Nina says she took them so that she can be as perfect as Beth.
Shortly after, Beth picks up the nail file on the table and says she’s not perfect as she starts stabbing her face. Nina tries to stop her, but she suddenly sees herself in Beth’s body, and that freaks her out, so she runs home.
Nina gets home, and as she switches off the light in the kitchen and heads to her room, she hears something. She turns the light back on and sees a bleeding Beth.
She immediately runs to the restroom as she believes she’s only seeing things. While she’s there, she hears her mom crying and goes to check, only to see her mom’s drawings talking to her. As she takes them off the wall while screaming, she looks into a mirror and sees Beth approaching her again.
However, she’s only hallucinating, and it’s Erica who is in the room. Seeing how stressed out Nina is, Erica tries to calm her, but Nina just runs to her room.
As she locks the door to prevent Erica from coming in, she starts feeling something coming out from a hole in her rash. As she takes it out, she looks into the mirror and sees that her eyes are now turning red.
With Erica still trying to come in, Nina goes to the door and bangs it against Erica’s hand until she’s able to lock the door. Her eyes continue to turn red, and it turns out to only be an imagination, and she also imagines her legs breaking before she passes out.
When Nina wakes up, she sees Erica, who says she had to stay with her, because she was scratching herself again. Nina asks for the time, but Erica tells her not to worry because she already called the theater, and told them that Nina is not feeling well and won’t be able to come. Nina doesn’t like this, and she immediately tries to go out. However, Erica has locked the door.
When she sees that Erica doesn’t want to let her leave, Nina gets violent and almost breaks Erica’s hand until she’s able to get the key. She runs to the theater, and on seeing her, Thomas and Lily are shocked to see her, with Lily already dressed as the Swan Queen and ready to perform in place of Nina.
Thomas goes to see Nina in her changing room, and tells her that he has already prepared Lily to get on the stage. Nina says since he has not announced it, then she can still do it. Thomas looks happy to see how confident Nina now looks.
Nina dresses up and goes out for her first performance, and as she’s very anxious and shaking while she’s lifted by her partner, he drops her. She’s, however, able to make up for that with a good recovery performance.
After the first act, Thomas is furious at Nina, but she says her partner dropped her. She has to immediately get dressed as the black swan, but as she enters her changing room, she sees Lily already dressed.
Lily tells her she’s worried because she will ruin the next act, so she’ll take over from her. Nina suddenly imagines Lily to be herself, and she gets violent and pushes her doppelganger against the mirror.
As her Black Swan twin tries to strangle her, Nina picks up a piece of the glass on the floor and stabs her. The body then changes back to Lily, and Nina is very scared about what has just happened.
She drags Lily into the bathroom, and then changes her dress for the next performance. Nina dances quite well to the delight of the audience.
But when she returns to her room to prepare for her final act, to depict the death of the white swan, she sees that Lily’s blood is already coming out of the bathroom. She places a towel at the entrance and starts changing.
Just then, someone knocks on the door, and to everyone’s surprise, it’s Lily. She is shocked as Lily tells her she’s really proud of her performance and she should finish it off with a wonderful show.
After Lily leaves, Nina checks the bathroom and sees that there is nothing. She, however, realizes that she has imagined everything that happened again. Nina also sees she stabbed herself while thinking it was her doppelganger she stabbed.
Nina manages to cover the blood, and goes out for her performance. She ends it very well, with the audience applauding her afterward.
While she’s still lying in the position of the White Swan’s death, Thomas comes to congratulate her, and tells her to stand up as he calls her his little princess.
However, he sees that she’s bleeding and calls for help.
While this is happening, Nina just starts saying that she felt what it was to be the white swan, and it was perfect.