Porter and Watson arrive at Porter’s apartment. Porter struggles with violent thoughts about his wife’s killer while Watson remarks on a photo of Heather; Porter explains she won a Shirley Jackson Award for writing. In the bedroom, Klozowski calls to report that a fingerprint from the railcar matched Watson, whose real name is Anson Bishop. Kloz realizes Bishop is with Porter. Using coded language, Porter confirms this. He draws his gun and enters the kitchen, but Bishop attacks from behind, stabbing him in the thigh near a major artery. Bishop forces Porter to the floor, makes him drop his weapon and phone, then crushes the phone. He warns Porter not to remove the knife and apologizes, saying they are nearing the endgame. He offers condolences about Heather and leaves as sirens wail.

Father asks Mrs. Carter if stolen items are in the box found under the Carters’ bed; she claims ignorance. Mother and Mrs. Carter begin fighting, but Father separates them. The diary narrator and Father eventually force Mrs. Carter to explain that her husband began copying files as insurance when he suspected his bosses were preparing to remove him. He planned to embezzle money into an offshore account so they could disappear, but she claims not to know if he succeeded or where he hid the copied documents. Father suggests the family should leave. Mother proposes killing the criminals first. Mrs. Carter warns that the man will return soon with others and that running is their only option.

Steven Mathers storms into Principal Kolby’s office demanding to know why his son Tyler is being questioned. Clair informs him Tyler may be involved in Emory’s kidnapping and possible murder. Mathers claims he has not spoken to his brother-in-law, Jacob Kittner, since his wife died five years ago, but Tyler confesses he and his mother secretly saw his uncle after learning he was dying. Clair dismisses Kolby from the office. She tells Mathers that Kittner had advanced stomach cancer. Nash reports that Jacob Kittner killed himself the previous morning.

Tyler explains that the detectives are wrong; his uncle wasn’t the Four Monkey Killer. Tyler’s father was having money troubles, which would’ve prevented Tyler from attending the Ivy League school he was accepted into. Jacob agreed to help Tyler find the funds, after which a mysterious man offered them money to help him with something. Tyler was told to get close to Emory, after which he discovered he genuinely liked her—he never thought Emory would be hurt. He was then told to steal Mr. Talbot’s expensive shoes. After that, Jacob was given the money for Tyler’s tuition. Tyler was then given the calculus textbook to leave at Emory’s home. Tyler’s father demands the detectives stop asking questions until they get their lawyer, and Clair receives an urgent text from Kloz to call him.

Less than an hour later, the diary narrator and his parents hear the car return. The man, now referred to as Mr. Stranger, revs the engine to announce his presence. Father walks toward the car, but it speeds away. Father returns and locks the door, explaining the men know Mrs. Carter is there and that she likely knows where the papers are hidden. Over coffee, Mother suggests drowning Mrs. Carter, but Father rejects this because Mr. Carter’s body is already in the lake. The diary narrator proposes strangling Mrs. Carter and placing her body in her car’s trunk at the train station to make it appear her husband killed her and fled. Father and Mother praise the idea. Mother says they should first find the papers and money as insurance to fund a potential relocation. Father agrees they will move the car during daytime for better cover. Mother eagerly volunteers to interrogate Lisa for the location.

Clair, Nash, and Kloz wait at the hospital for news on Porter. Nash blames himself for not recognizing Bishop as an impostor. Kloz explains Bishop faked his CSI credentials by creating false records. After Kloz voices his guilt, Nash punches his shoulder before Clair insists it is not his fault. A doctor reports Porter is stable and recovering. In his room, Kloz apologizes, and Porter absolves him. Kloz says Bishop’s photo has been released to the media and that Bishop used Kittner’s address on his employment records. Clair updates Porter that Kittner was paid to kill himself and that Tyler planted evidence. Nash concludes Watson/Bishop is the real Four Monkey Killer. Porter says Bishop’s cover being blown means he will accelerate his plans for Emory. Porter remembers they signed in at the precinct, meaning Bishop left contact information. Nash calls and learns Bishop wrote down a new address: Berwyn Apartments on LaSalle. Porter agrees Bishop will kill Emory to punish Talbot and decides to finish reading the diary while hospitalized.

When the music tormenting Emory stops, she experiences crushing silence and a migraine. A hallucinated voice urges her to eat a rat to survive. Her cuffed wrist is infected, swollen to twice its normal size, and broken at an unnatural angle. She refuses to eat despite the voice’s persistent arguments. Suddenly, a bright light floods the room from high above. A shadow moves overhead, and Anson Bishop apologizes for taking so long to visit, saying he has been very busy.

The diary narrator wakes around eight o’clock in the morning to find Father passed out on the couch with an empty rum bottle. They had slept dressed to react quickly if Mr. Stranger returned. After the diary narrator makes breakfast, Father wakes and looks outside in shock. The Carters’ car is back in their driveway with clothing strewn across both yards. Father’s Porsche has been extensively vandalized and rendered unusable. Mother’s Ford Tempo also has four flat tires. The diary narrator notices that the hood on her car is up as well. The Carters’ front door stands wide open.

Bishop calls Porter’s hospital room from a burner phone. When asked about Emory, Bishop avoids answering but speaks of her in the present tense, hinting she’s alive. He outlines his philosophy: punishing fathers through their children is the ultimate consequence for sins, causing lasting regret rather than simple imprisonment. He tells Porter the answer is in his hands, referencing the diary. Bishop says he posed as a CSI to understand Porter better. He mentions leaving fresh boxes and suggests Clair and Nash may find them. He signs off with a taunting countdown. Porter rises from bed, dons surgical scrubs, and retrieves the evidence bag containing the pocket watch. Seeing it triggers a realization.

The diary narrator, Father, and Mother enter the ransacked Carter house. The diary narrator notes the Carters’ car received less personal vandalism than Father’s Porsche. Inside, every room has been torn apart: the refrigerator left open, cabinets emptied, furniture sliced open and gutted, books shredded. On the kitchen table, the diary narrator finds six photographs of Mother and Lisa naked together in bed. He quickly hides them in his pocket before his parents can see.

Clair and Nash race through rush-hour traffic to the Berwyn Apartments on LaSalle. They rendezvous with Espinosa and his tactical team outside Bishop’s building. Espinosa’s team breaches and clears the apartment. Inside, the space is completely bare—no furniture, unused kitchen, empty walls. In the center of the living room sits a single white file box tied with black string.

As the diary narrator and his parents search the Carter house, they hear the green Plymouth Duster approaching. All three run back to their own house. As they get inside, they hear a rifle bolt. From outside, Mr. Stranger calls out to them, taunting the family.

Porter leaves the hospital and takes a cab to Lost Time Antiques. The cabbie notices Porter looks like an escaped patient but locates the address at 316 West Belmont. During the ride, Porter resumes reading the diary.

A bullet fired by Mr. Stranger narrowly misses the diary narrator’s head and hits the doorframe, sending wood splinters into his cheek. Father shoves the diary narrator inside and closes the door but is shot in the shoulder in the process. Mother examines the wound and determines it is only a graze. The diary narrator retrieves a first-aid kit and damp towel. Mother cleans and bandages Father’s shoulder.

Espinosa confirms his team has not opened the box found in Bishop’s apartment. Nash hesitates, but Clair urges him to open it. Nash unties the black string, removes the lid, and peers inside, reacting tersely.

Mr. Stranger taunts the diary narrator and his parents from the porch, claiming he knows they have the paperwork and are hiding the Carters. He explains he deduced their involvement because the staged train station scene was too clumsy for Mr. Carter to have orchestrated. Mother sees Mr. Smith, the wiry man, outside a window tapping the glass with his rifle. Father signals Mother to retrieve knives; she returns with two large kitchen knives and hands one to Father. Mr. Stranger reveals Mr. Smith has doused the entire house, including the roof and trees, with gasoline. He gives them a five-minute ultimatum: Come out with the Carters, or the house will burn with everyone inside.

The cabbie notices Porter’s wound is bleeding. They arrive at the shop, which closed 15 minutes earlier. Porter sees a woman leaving the adjacent dry cleaners. He checks the parking meter and realizes the rate—75 cents per hour—matches the change found in Kittner’s pocket. Porter borrows the cabbie’s phone and calls Kloz for the dry cleaner receipt number: 54873. He enters the cleaners, gives the clerk the number, and receives Emory’s cleaned jogging clothes and shoes.

The diary narrator’s Father sends Mother to retrieve Mrs. Carter from the basement while instructing the narrator to heat vegetable oil on the stove. Mother brings the cuffed, partially undressed Mrs. Carter upstairs. Father shouts to Mr. Stranger that Mr. Carter is dead and offers Mrs. Carter in exchange for their departure. Mrs. Carter warns the men will kill everyone anyway. Mr. Smith attempts to break through a kitchen window; Father rushes over and slashes his fingers with a knife. Father grabs the boiling pot of oil from the stove. The diary narrator proposes they split up and steal the attackers’ car, but Father insists it must end here. Mrs. Carter offers Mother and Father half of the $14 million her husband stole if they save her and reveals the paperwork is in four safe-deposit boxes at Middleton downtown. When she refuses to reveal where the keys are hidden, Father threatens her face with boiling oil. Burned by spattering drops, Mrs. Carter screams that the keys are hidden “under the cat” (347). The narrator realizes she means his buried cat’s grave by the lake. Mr. Stranger shouts that their time is up.

Nash pulls a note from Anson Bishop out of the box and reads it aloud. The note states the box contains evidence against Talbot and that Bishop is about to execute both Talbot and possibly Emory. Clair tries to reach the patrol car assigned to Talbot but gets voicemail; dispatch cannot reach them either. Nash discovers the box contains old handwritten financial ledgers written in code, dated back nearly 20 years. At the bottom, Nash finds a manila envelope filled with Polaroid photographs of a naked adolescent girl.