At 1:17 pm, Detective Clair Norton approaches a group of parents at the playground at A. Montgomery Ward Park. She asks if they know anything about Emory’s disappearance, as Emory was running there last night. Two adults recognize the photo of Emory. They explain they saw a man carry her from behind some trees the previous day, claiming she had fallen and hit her head, that he knew her, and he was taking her to the hospital. The witnesses provide conflicting descriptions of his vehicle, disappointing Clair. Clair instructs them to wait for officers to take formal statements, then briefs Lieutenant Belkin before calling Porter.

The diary narrator follows Father into the basement and discovers Mr. Carter handcuffed to a water pipe in the corner. Mr. Carter is gagged and covered in blood; his chest is riddled with deep cuts. Mother descends the stairs and explains that Mr. Carter beat his wife, then came to their house and made sexual threats toward her. She confesses to pushing him down the stairs, chaining him up, and spending hours cutting him in an attempt to slice the evil out. When Father asks if this is true, Mr. Carter shakes his head violently. Mother calls him a liar and plunges a knife into his abdomen, then stabs him again in the thigh with such force the blade strikes concrete. Father watches calmly. The diary narrator smiles, believing Mr. Carter deserves punishment for beating Mrs. Carter.

Porter and Nash arrive at Whatney Vale High School at 1:38 pm. They meet with Principal Kolby, who confirms that Emory Connors is not enrolled there. Kolby summons Tyler Mathers, Emory’s boyfriend, to his office. Porter informs Tyler that Emory has been kidnapped. The distraught teenager explains that Emory is homeschooled by a tutor named Ms. Burrow and says he has been unable to reach her since the previous day. Nash mentions that Emory’s phone has been offline since yesterday, and Tyler reveals she had a second phone.

After showering, the diary narrator returns to the kitchen to eat beef stew. He reflects that Mr. Carter died from fear rather than blood loss. Father removed Mr. Carter’s eyes while Mother continued cutting. They used smelling salts to revive him from unconsciousness before torturing him again, but his heart eventually gave out. Mrs. Carter, badly bruised, appears at the kitchen door searching for her husband. The diary narrator tells her he will ask Mother and bounds down the steps into the basement.

At 3:03 pm, Porter and Nash meet with Kloz in the IT department. Kloz displays surveillance footage showing a man in a fedora stepping in front of a city bus. The video reveals he deliberately shielded his face with the hat while jumping. Witnesses provided no description. Kloz believes the suicide was staged to be visible but not identifiable. Porter theorizes that everything about the man’s death was intentional, including all items found on his body. Nash remains skeptical. Porter receives a call that Nancy Burrow has been located at Flair Tower.

The diary narrator finds his parents rolling on the blood-soaked basement floor, laughing. He informs them that Mrs. Carter is at the back door, looking for her husband. Father asks the narrator to send Mrs. Carter away. The narrator briefly fantasizes about having her chained in the basement before agreeing to handle the situation.

At 3:34 pm, Emory huddles naked and handcuffed beneath a gurney in darkness. Deafening music has played for hours, drowning out her screams. She is freezing, in pain from the handcuffs, and suffering a migraine. An internal taunting voice torments her thoughts. Something scurries over her foot, terrifying her. The voice suggests it might be a rat and describes how rats might attack her. She scrambles atop the gurney for safety and glimpses a rat in the shadows.

Returning upstairs, the diary narrator finds Mrs. Carter has entered the kitchen uninvited. He lies that his parents are fixing the water heater in the basement, but Mrs. Carter flatly infers her husband is dead. The diary narrator realizes he must tell her the truth to prevent her from calling the police. He confirms that her husband is dead, explaining that Mr. Carter tried to hurt Mother and she defended herself. As Mrs. Carter cries, the diary narrator offers to take her home.

At 4:17 pm, Porter and Nash arrive at Emory’s apartment, where Officer Murray directs them to Nancy Burrow. She explains she last saw Emory the previous evening before her run and assumed she stayed at her boyfriend’s house. Nash aggressively questions her lack of supervision, and Burrow defends herself, stating she is Emory’s highly qualified tutor, not her mother. Arthur Talbot, Emory’s father, made clear that her role doesn’t extend beyond tutoring. Burrow reveals that Talbot is normally cold and distant regarding Emory but was uncharacteristically emotional when he called about the abduction. She mentions a mysterious calculus textbook that appeared three days ago, which Emory claimed not to have purchased.

The diary narrator escorts Mrs. Carter home and pours her bourbon, which she drinks rapidly before offering him some. As they continue drinking together, she becomes emotional about her husband, Simon. Mrs. Carter confesses she knew the diary narrator was at the lake the other day and wanted him to see her naked. She asks if he thinks she is pretty, and he nods, feeling aroused. After consuming more bourbon, she drops the bottle, which shatters, then passes out at the table. The narrator leaves to get his parents to help tie her up.

At 4:49 pm, Porter, Nash, and Watson examine the mysterious calculus textbook in Emory’s den. Watson identifies the book as an out-of-print edition last in pristine, unused condition. Dusting for fingerprints, he finds only one set that likely belongs to Nancy Burrow. After Nash nervously suggests the book could be a bomb, Watson opens it safely. Porter wonders why the Four Monkey Killer, who has never left clues, would leave one now. Watson discovers the publisher’s address, a location in the Fulton River District, on a page with a faint dog-ear crease, which indicates the killer wanted it found. Porter calls Kloz, who reports the address belongs to the condemned Mulifax Publications warehouse, scheduled for demolition in two days. Porter and Nash recognize the parallel to a previous victim, Missy Lumax, whose body was found in a similar warehouse in the same district.

The diary narrator wakes with a severe hangover the following morning. At breakfast, Father gives him a shot of bourbon as a hangover cure and makes him promise to remember this as his true first drink—a bonding moment with Father—and forget the previous night with Mrs. Carter. Father reveals that Mrs. Carter is now their guest in the basement and wonders what she did to provoke her husband’s violent behavior toward Mother. When Father probes whether Mr. Carter or the narrator witnessed anything, the narrator lies, denying he saw anything. Father tasks him with taking breakfast to Mrs. Carter and says he will stage the Carter house to appear they left on a trip. The diary narrator impresses Father by suggesting they move the Carters’ vehicle as well.

At five o’clock at night, the music abruptly stops, leaving Emory with severe tinnitus. Alone in complete darkness on the gurney, she cannot see anything. Terrified that her captor might be in the room preparing to take her eyes, she tries to stay calm. When the ringing fades, she hears steady dripping and decides to search for water despite her fear. She leaves the wall and shuffles forward in the darkness, dragging the gurney behind her. Rats scurry over her feet, triggering a cathartic scream that releases her pent-up frustration. She locates a large, bolted metal plate on the floor where water is dripping. Desperately thirsty, she stretches toward the water while handcuffed to the gurney. She briefly tastes the rusty water before the gurney tips over, crashing down on her back and slamming her head against the floor, knocking her unconscious.

The diary narrator prepares a breakfast tray and descends to the basement, passing Mother on the stairs. She smells of bleach and blood. He finds Mrs. Carter handcuffed to a cot near where her husband died. When he removes her gag, she screams for release. To silence her, the diary narrator pulls a knife and pricks her neck before replacing the gag. Father arrives and begins explaining the family’s rules based on the wise monkeys. The diary narrator enthusiastically joins in, naming the three monkeys: Mizaru (see no evil), Kikazaru (hear no evil), and Iwazaru (speak no evil). Father explains the fourth and most important monkey, Shizaru, represents do no evil. He states that Mr. Carter violated this rule but plans to discover what Mrs. Carter did to provoke him. The diary narrator worries about Mother’s involvement but remains silent. Father leaves, instructing that their guest is not allowed utensils.

At 5:23 pm, Porter, Nash, and Watson conduct surveillance on the condemned Mulifax Publications warehouse in the Fulton River District. Watson reveals the building sits near old bootlegging tunnels. Clair arrives with a SWAT team disguised in a plumbing van. They theorize that the Four Monkey Killer used these tunnels to transport victims undetected. The team breaches the warehouse. Deep inside, they hear gunfire and discover the basement is infested with thousands of rats. Porter observes the rodents fleeing toward a single door in the corner. Sergeant Espinosa’s team breaches the door and finds a room reeking of decay, lined with burned-out candles. An overturned hospital gurney sits at the center with a naked, partially devoured body handcuffed underneath.

The diary narrator removes Mrs. Carter’s gag. This time she remains quiet. He gives her orange juice. Mrs. Carter attempts to seduce him, promising sexual favors if he releases her. The diary narrator ignores her offer and insists she eat, holding a banana to her mouth. She takes a bite while continuing to flirt, calling him a good boy.

Porter clears rats from the body and sends Clair to summon CSI and the Medical Examiner (ME). Examining the corpse, he determines it is not Emory but a male in his fifties with graying hair. A skull fracture suggests the victim fell from the gurney. Based on beard growth, Porter estimates the man was alive for two to three days before dying. The gruesome sight causes Nash to vomit. Porter pries open the victim’s clenched fist and finds a brochure for The Moorings Lakeside, a Talbot Estates development. Espinosa reports that his team discovered a tunnel entrance. Porter instructs Nash to wait for the medical examiner while he investigates the tunnel with SWAT.

Father presents the diary narrator with his old red wagon loaded with plastic-wrapped packages containing Mr. Carter’s dismembered body. Because he has been called to the office, he instructs the narrator to take them to the lake, weigh them with rocks, and throw them in the water. Then, the diary narrator must stage the Carter house to make it appear they left on a trip. Father will dispose of the Carters’ vehicle later. Finally, Father asks the diary narrator to monitor Mother, who becomes emotionally unstable after she kills. The diary narrator reflects on his mother’s unpredictable post-kill moods—either complete withdrawal or manic elation. He begins pulling the heavy wagon toward the lake.

At 6:18 pm, Espinosa’s team shows Porter the tunnel entrance concealed behind crates. Inside sits a railcar with freshly oiled wheels. Officer Thomas lifts a partial fingerprint. Porter realizes the Four Monkey Killer likely used this extensive tunnel network to transport victims throughout the city for years. The team enters, losing communication as they descend. Espinosa marks their path with spray paint. After 20 minutes, they reach an illuminated chamber with a ladder leading to a manhole. On the floor are three white boxes; one is labeled “PORTER.” Inside are a human ear, a pair of eyes, and a tongue—presumably from the warehouse victim. Espinosa and Porter climb the ladder and open the manhole into the Moorings Lakeside residential development.