In his freshman year, Easton Bradley Sinnett, “Sin,” wakes up to men rushing into his room. They drug him, and he wakes up in a room with other initiates. Lincoln, the Lord in charge, tells them they are being challenged. Sin remembers his father telling him that a real man needs to kill someone. Failing a challenge will end the initiation and make the failed initiate a target for life. Lincoln brings in a man with a hood over his head, and Sin volunteers to kill him. Sin slits the man’s throat.

Sophomore year, Sin gets an assignment and rides his motorcycle to a mansion he has visited before. He sneaks in through a second-floor bedroom, which belongs to Ellington Jade Asher, the daughter of a notable Lord, James. Sin’s assignment is to kill James, but he gets distracted by arousing thoughts about Ellington, or “Elli.” Sin has been obsessed with Elli for years, and he is familiar with her home and father.

Sin finds James in a bathroom and shoots him. Sin takes James’s phone and cuts off one of his fingers to unlock it. Elli interrupts and starts to scream, but Sin covers her mouth, brings her to another room, and binds her hands. Sin is wearing a mask and colored contacts, so Elli does not recognize him. Though Sin cannot have sex until he is a senior, he sexually assaults Elli with the barrel of his gun. Sin gives Elli a knife to untie herself and tells her to keep the murder and sexual assault a secret. Sin leaves but sees Elli standing on a balcony. He checks James’s phone and discovers why Elli is not telling anyone about the murder.

Junior year, Sin breaks into Lance’s house and waits for him to use his indoor sauna. Lance is a Lord who betrayed the oath, though Sin does not know or care about the details. Sin replaces the water in the steam room with acid, which burns Lance when he pours it on the heater. Sin tells Lance he deserves to die for breaking the oath and watches Lance slowly die from acid burns. Sin is excited to visit Elli, noting that he visits her after each initiation.

Five weeks before the beginning of his senior year, Sin and 14 other initiates kneel in front of Lincoln to complete their initiation. 25 initiates had begun the process with Sin, but 10 failed. Next to Sin is his friend, Jayce, and another initiate, Ryat. Lincoln gets to Sin’s turn, heating an iron to brand Sin’s chest. Other Lords restrain Sin, and Lincoln welcomes Sin into the society by branding him.

Two weeks into the new semester, Sin plays poker in the house of Lords, in which all initiates and Lords live during their time at Barrington. The next day, the new Lords will be given their “chosen” Lady, but Sin is uninterested. Jasper, another new Lord, urges everyone to draw papers from a vase. Each paper has the name of a woman attending Barrington. Ryat refuses and leaves the room, and Jasper reveals that he drew Elli’s name. Sin is upset, and Lincoln asks to speak with him privately. Lincoln gives Sin photos of a man he wants Sin to investigate, and Sin is frustrated that this man has gotten into Elli’s life. Sin showers and remembers how he performed sex acts on Elli with a knife handle two weeks after he sexually assaulted her with a gun.

Sin pays some men to steal Elli’s car, which is the only vehicle parked outside Sin’s mark’s house. Jayce calls to tell Sin that he is missing the ceremony to receive a “chosen,” but Sin tells Jayce to take the woman intended for Sin. Sneaking into the house, Sin finds Elli blindfolded and tied to a bed in a sex dungeon. Knowing Elli expects the owner of the house to come in and have sex with her, Sin decides to take his place. Sin thinks of Elli as his “little demon,” and he pokes a hole in the condom he intends to use. Sin has sex with Elli, makes her drink a vial of some drug, and puts a sweatshirt on her. The men text Sin that they accomplished their task, and Sin carries Elli out of the house.

In class, Elli reads a journal entry in which she describes being used for sex by three men. The professor ends class and compliments Elli, and Elli’s friend, Kira, praises the story for arousing her. A classmate, Mack, praises the story, as well, and Kira reveals that she recently had sex for the first time. Elli thinks about the mysterious man who periodically breaks into her room to have sex with her, and she notes that he has not appeared in two months. She texts him, asking if he can visit that night, but he ignores the text. Elli is hurt but accepts that men do not “stay around.”

Sin

Sin sneaks into Elli’s bedroom in his mask and hears her in the shower. He hides behind a curtain and watches as Elli gets into bed. Elli’s mother calls, and she claims she was out with Kira, which Sin knows is a lie because Kira is his sister. Elli masturbates blindfolded, and Sin masturbates, as well, debating whether he should interrupt Elli. They both orgasm, and Sin hides behind the curtain before Elli removes her blindfold. She sends a text message and goes to sleep, and Sin sees that she texted him to say that she does not need him.

Elli goes to Kira and Sin’s house, greeting Mrs. Sinnett as she leaves. Kira is not ready to leave, and Sin appears in the kitchen with his friends, Jayce and Corbin. Sin taunts Elli, and she is frustrated that Sin is attractive but annoying. Elli texts a man with whom she has been having sex for two months, and Sin comments that she has a boyfriend. Elli does not think Sin would ever act on his jokes about having sex with her, but she is aroused. Kira enters, and she and Elli leave.

Sin

After Kira and Elli leave, Jayce chastises Sin for missing the ceremony, and Corbin hands Sin a notebook. Sin gets a text from Sandy, a friend of his mother who has had sex with both Sin and Jayce. Sin’s father enters and wants to talk to Sin, but Sin avoids the conversation, knowing it is about missing the ceremony. Sin wants to make Elli his, and he is not interested in any “chosen” Lady from the society.

Elli recalls her mother’s work as a sex therapist. Elli would listen to her mother’s sessions with clients, from which she learned about sex as a child. One couple stands out to Elli, Mr. and Mrs. Taylor. Mr. Taylor wanted to watch his wife have sex with other men, and she sometimes agreed to fulfill this fantasy. Mrs. Taylor did not like having sex with other men, but Mr. Taylor refused to have sex with her. Mr. Taylor drugged his wife, invited two of his business partners to their home, and had them sexually assault Mrs. Taylor on camera. Mrs. Taylor demanded a divorce, while Elli’s mother reported Mr. Taylor to the police. Mr. Taylor’s partners were arrested, and Mr. Taylor died by suicide. Mrs. Taylor discovered she was pregnant and decided to keep the child, lamenting that her child will not have a father. Elli concluded that some sexual impulses need to be suppressed. When Sin told Elli he loved her eyes and wanted to cut them out as trophies, she became aroused and realized her unique sexual tastes. She hopes the masked man will make her “his.”

Elli goes to her psychology of human sexuality class and resumes her story. They read sexual stories to prepare for careers in sex therapy. Elli’s notebook is missing and she panics. Sin, Jayce, and Corbin enter, displace students on either side of Elli, and give her the notebook. Elli reads the rest of the story, in which three men have sex with her while she is bound. After the story, Sin and his friends tell everyone to leave, including the professor. When everyone leaves, Sin uses his belt to tie Elli’s wrists, and Corbin keeps her in her seat. Sin calls Elli “little demon,” a nickname from when Elli took the blame for Kira setting Sin’s tent on fire during a camping trip. Sin takes off Elli’s pants and uses his hand to bring her close to an orgasm while Jayce covers her mouth and nose. Sin stops abruptly and tells Elli to come to an event that night. Sin, Jayce, and Corbin leave.

Sin tells Elli to go to The Freak Show, an abandoned fairground that was restored as a year-round Halloween fair. Elli puts on her bunny costume and arrives at the fair, where Sin texts her a cryptic, Halloween-themed message. She enters a house of mirrors and becomes disoriented, reflecting that she is aroused by suspense and the unknown. In a circular room of mirrors, Elli cannot open the door, and three men in costumes appear. They chain Elli to the ceiling, rip off her clothes, and attach something painful to her nipples.

Sin

Sin is aroused, and he notes that Corbin and Jayce are only allowed to help set the scene, insisting that no one can have sex with Elli except him. Sin uses his hand to bring Elli close to an orgasm before stopping, telling her that they are only beginning.

The three men unchain Elli and put her costume back on. One of them carries her, and they go to a rollercoaster. The men tie Elli’s hands behind her back, force her legs apart, and insert a cold object in her vagina. Sin’s voice tells Elli she is about to get her wish, and they blindfold her before securing the safety bar and activating the rollercoaster. Elli screams and has an orgasm as the ride continues. She never wants it to end.

Sin

Sin, Jayce, and Corbin bring Elli, who fell unconscious on the rollercoaster, to her home. They restrain her arms and bind her ankles. Sin notes how they pierced her nipples. Jayce finds Elli’s diary, in which she laments that David, the man she is dating, does not approve of her sexual interests. Another entry confesses her fantasies about Sin. An entry from the day Sin killed Elli’s father reveals that Elli wanted her father to die. Jayce and Corbin leave, while Sin waits for Elli to wake up.

Sin waits in Elli’s room for David to show up. Elli is unconscious, and David enters, walking to her nightstand and musing about her nipple piercings. David is Elli’s professor for her psychology of human sexuality class. Sin interrupts and tells David to end his sexual relationship with Elli, threatening to file charges against David or kill him. David refuses, and Sin punches him, calling Corbin and Jayce into the room. Sin orders Jayce and Corbin to destroy David’s computer files, threatens David with a gun, then tells his friends to take David away.

Ellington

Elli wakes up and sees Sin take off his mask. Sin tells her he is going to make her “his,” and he takes off his clothes, revealing the piercing in his penis. Elli is aroused, and Sin caresses her, explaining that he has always wanted to have sex with her. He muses about having anal sex with Elli and promises to reward her for being good.

Sin forces Elli into anal sex, repeating that she belongs to him. Elli has not had anal sex before, so Sin sees this sex act as a form of claiming her body. Elli struggles against him, and they both orgasm. He is frustrated thinking about Elli having sex with other men, including her diary entries about the masked man she did not know was Sin. Sin forces Elli to perform oral sex on him.

Ellington

Sin climaxes and leaves the room. Elli liked the sexual experience, but her arms hurt. Sin comes back, picks Elli up, and carries her to the bath. He tells her she is perfect, and she notices one of her diaries on the counter. Elli’s diaries contain her darkest fantasies, and she has been recording her thoughts on sex since she was a child. Sin asks if Elli trusts him, and she does. Sin chokes her and holds her head under the bathwater, fulfilling a fantasy from her diary. He brings her out of the water before she runs out of breath.