A math teacher reprimands a student named Bárbara for a note she purportedly wrote. After insulting the teacher, she performs a hand-trick illusion with the note.
A girl dancing to the sound of Japanese music faints in her bedroom. A man sells his belongings (books) at a used goods store and looks with interest at a jewelry store's display window, later arriving home to find the girl, Alicia, lying unconscious on the floor.
Back home from the hospital, the man Luis, Alicia's father, grants Alicia, known as Yukiko in her otaku circle, a number of wishes. Upon reading Alicia's diary, he commits to gifting Alicia a Magical Girl Yukiko costume costing €6,845, and asks a bar owner Marisol for money to satisfy the secret wish of his 12-year-old daughter.
A desperate Luis decides to break the aforementioned shop window glass, but vomit falls on him from above just before breaking it. A man and a woman, Bárbara, discuss in their bedroom, after which Bárbara pretends to ingest her medication. After taking a friend's baby in her arms, Bárbara jokes with throwing the baby out of the window. Bárbara wakes up at night and hurts her forehead with a mirror. After ingesting alcohol and pills, she vomits out the window on Luis, and invites him to her apartment so he can take a shower. Upon learning that Bárbara's husband is a rich psychiatrist and after presenting himself as an unemployed literature teacher named Pedro, [Luis] has sex with Bárbara.
After claiming to have recorded them having sex with his phone, Luis blackmails Bárbara into getting him €7,000, threatening her with telling her husband. Bárbara asks a madam named Ada for money, offering to prostitute herself, thereby getting a one-time job without penetration at Óliver Zoco's residence. Taken to a remote mansion by a chauffeur-driven car, Bárbara is asked there to remove her clothes and to remember a BDSM safeword ('hojalata') before entering a room.
Luis asks Bárbara to leave the money inside a Spanish Constitution book hosted in a public library near Puerta de Toledo. After gifting the dress to Alicia, Luis finds out that the set is missing the scepter, sold as an add-on. Luis then blackmails Bárbara again into giving him another €20,000. Bárbara offers to do a job behind Óliver's black lizard door, where unspeakable things are done, discouragement by Ada notwithstanding.
Introduced as [Damián], the teacher from the opening scene (now an old man) does not want to leave prison, because he is afraid of seeing Bárbara again. Damián finds a badly wounded Bárbara lying on the stairs of his apartment and takes her in, calling an ambulance. Bárbara asks Damián to leave the Constitution in the public library. Bárbara's husband, introduced as [Alfredo], thanks Damián for taking care of his wife. At the hospital, Bárbara falsely suggests to Damián that she has been raped by her blackmailer.
After obtaining a gun, Damián follows Luis into a bar, introduces himself to him as a man sent to prison for having helped Bárbara, and provides Luis with the gun so he can kill him in plain sight, threatening to kill Luis' family otherwise. Failing to believe Luis's version of the events and convinced that Luis raped Bárbara, Damián kills Luis and the two other witnesses at the bar. Damián goes to Luis apartment to look for the latter's phone, meeting Alicia, fully dressed with the Yukiko Magical Girl dress and holding the scepter. Damián shoots her. Damián visits Bárbara and tells her that he has taken care of everything, playing on her the same trick with the phone that she played on him with the note years ago.