Buffy searches newly rented houses for the Trio's hideout and the three discover her on their surveillance equipment, as she gets a bit too close. While they hide in the basement, Andrew calls on a demon that attacks Buffy and starts a fight. The demon grabs Buffy and stabs her with a needle-like part of its body. In a mental hospital, Buffy cries out as she's held by two orderlies and stabbed with a needle. Buffy wakes up alone outside the Trio's house, hurt and confused and walks home.
Willow prepares herself for talking to Tara, but spots Tara greeting another woman with a quick kiss and Willow walks away, wounded. Tara notices her retreating, but it's too late to chase after her. At the Doublemeat Palace, Buffy works like a zombie, and flashes to the mental hospital where a doctor announces it's time for her drugs. Willow and Buffy talk about Xander's disappearing act and Willow's attempt to talk to Tara. Xander surprises the girls by showing up at the house, and wonders about Anya and how to repair his relationship with her. The girls tell him Anya left a few days ago and try to reassure him that everything will work out in time.
Buffy runs into Spike at the cemetery and they talk about the events of the wedding that didn't happen. A confrontation begins between Xander and Spike and as Willow tries to break it up, Buffy gets weak and collapses. Xander manages one punch to Spike before his attention is drawn by Buffy. At the mental hospital, a doctor informs Buffy that she's been in the hospital for six years and everything she knew to exist in Sunnydale isn't real. She's shaken and confused, especially when both of her parents appear, and then Buffy falls back into the Sunnydale world.
Willow and Xander get Buffy home and she recounts what she saw and was told at the mental hospital. While Willow organizes a plan to research, Buffy falls back to the mental hospital reality. The doctor explains to her parents that she's been suffering from schizophrenia and her life as the Slayer has been an imagined story she made up in her mind. In Sunnydale, Warren and Andrew return to their hideaway with boxes after leaving Jonathan alone. Leery, Jonathan questions the contents of the boxes and tries to leave the house himself. Warren doesn't agree with that idea and convinces Jonathan to stay in the basement.
Willow shows Buffy a picture of the demon that stung her and tries to comfort her friend. Buffy confesses to Willow that in the beginning of her Slayer life, she told her parents about vampires and was put in a clinic for her supposed insanity. Buffy wonders if she's still there and Sunnydale really doesn't exist, but Willow assures her that isn't true. Xander and Spike patrol for the demon that hurt Buffy and between the two of them, they subdue the demon with force and tranquilizer darts. Dawn brings Buffy some tea and dazedly, Buffy observes that Dawn has been misbehaving and the problems need to be dealt with.
At the hospital, Joyce tells Buffy that Dawn doesn't exist and as soon as she's better, they can go home. Dawn realizes through Buffy's babbling that she doesn't exist in the other reality and upset, she leaves. In Sunnydale, the demon is dragged downstairs and held down as Willow hits it and then breaks off its stinger. She sends Xander on a mission for supplies at the Magic Box for an antidote that she must make without the help of magic.
Later, Willow presents the antidote to Buffy, and Spike drops by to check on Buffy. She tells him to leave but Spike responds with a lecture about her love of pain and misery and tells her to tell her friends about their relationship before he does. Buffy starts to go for the antidote, but stops and pours it out into the trash. At the mental hospital, Buffy tells the doctor and her parents that she wants to be healthy and be rid of thoughts of Sunnydale. The doctor tells her that she has to do what is necessary to destroy the elements that draw her back there, like her family and friends, to truly be healthy.
Xander arrives at the Summers house and finds Buffy alone in the kitchen. He talks to her about Spike and his obsession then she knocks him out cold and drags him into the basement. Willow is bound and gagged there already with the demon chained to a beam, but there is still someone left for Buffy to get rid of. Upstairs, Buffy finds Dawn packing in her room, and tells her sister that she must go downstairs with everyone else. Dawn runs and tries to convince Buffy not to hurt her, but is ultimately bound and gagged in the basement with the others.
In the mental hospital, the doctors convince Buffy to pace herself while in the Sunnydale reality, and Buffy unchains the demon in the basement. Xander pleads with Buffy to help him, but she retreats under the stairs, leaving the demon to take her friends. Meanwhile, Tara shows up at the house and finds everyone in the basement. She uses magic to free Willow and Dawn and sends a shelf full of paint flying at the demon. At the hospital, Joyce encourages Buffy to fight against the Sunnydale reality, telling her that she has the strength to fight against the harshness of the world and she has people who love her. Buffy, inspired by her mother's words, realizes what she really needs to fight against. She thanks her mother for the wise words and leaves that reality to return full-force in Sunnydale and destroy the demon trying to hurt her friends. At the hospital, the doctor checks Buffy and tells her parents that she's gone catatonic. The ending leaves viewers to wonder if Buffy is in fact a Vampire Slayer, or this universe is merely a figment of her imagination.