The Black Book

The story opens in present-day Chicago as Detective Patti Harney races to a crime scene at a sixth-floor condo where three people have been shot. In the bedroom, she finds Detective Katherine Fenton, her brother Billy's partner, dead with a gunshot wound above her eye. Amy Lentini, an assistant state's attorney, lies dead on the bed. Billy Harney, Patti's twin brother and a Chicago Police Department detective, sits upright on the bed with blood running down his face. Lieutenant Wizniewski, known as "the Wiz," suggests that Kate walked in on Billy and Amy, opened fire, and Billy shot back. Patti silently rejects this theory. Then medical personnel discover Billy still has a pulse.

The narrative shifts to several weeks before the shooting. Billy, who narrates much of the novel in first person, stakes out a Gold Coast brownstone, targeting a wealthy trader he suspects of murder. Billy and his team, including partner Kate Fenton, observe prominent men entering, among them Archbishop Michael Xavier Phelan and Mayor Francis Delaney. The Wiz, Billy's supervisor, urges him not to raid the building, but Billy insists. Inside, the team discovers a hidden basement sex club. Billy arrests everyone, including the mayor, who tries to bribe him. Kate handles the evidence search but finds no records and no client ledger, the so-called little black book that a brothel of this scale would certainly maintain.

Billy and Kate celebrate at the Hole in the Wall, a cop bar where Billy performs stand-up comedy. Lieutenant Mike Goldberger, known as "Goldie," is Billy's longtime mentor and head of the Bureau of Internal Affairs (BIA). Goldie warns that powerful people will retaliate. That night, Billy and Kate sleep together for the first time. Police Superintendent Tristan Driscoll, State's Attorney Margaret Olson, and Amy Lentini aggressively question the detectives, with Amy implying a cop stole the black book. Goldie halts the meeting by invoking the detectives' right to union representation, but both are placed on administrative leave. Billy confides to Goldie that the controversy is a pretext: He has been working undercover for the BIA for 18 months, investigating a protection racket he believes the Wiz runs.

The narrative returns to the present, roughly two and a half months after the shooting. Patti and her family keep vigil at Billy's hospital bedside. His survival is extremely unlikely: The bullet passed through one brain hemisphere, and he lost brain activity for about 30 minutes. A ballistics report delivers worse news: Amy was shot not by Kate's gun but by Billy's, indicating Billy fired first. Billy slowly regains consciousness, his memories fragmented. He remembers the mayor's arrest and his suspension but nothing after his conversation with Goldie. Patti reveals that Kate is dead and warns Billy not to believe anyone's account. After 98 days, Billy leaves the hospital determined to play the part of a diminished, harmless man while secretly investigating. He begins sessions with Dr. Jill Jagoda, a psychologist who concludes his memory loss is psychological rather than physiological.

The past timeline resumes after Billy and Kate return to duty. As they prepare for trial with Amy, both partners openly question whether the other stole the black book, and their trust fractures. Goldie advises Billy to stay close to Amy and to find the ledger, and Billy begins investigating on his own. He discovers his sister Patti meeting secretly with the brothel's manager, Ramona Dillavou. He also identifies the Wiz as the person tailing him by staging a fake handoff at a subway station with undercover BIA Sergeant Joe Washington. The next morning, Washington is found murdered execution-style. Billy and Goldie suspect the Wiz but refuse to reveal Billy's undercover status.

Billy and Amy begin a romance that revives emotions Billy has not felt since his wife Valerie died by suicide after their daughter's death from a stroke. Shortly after their first date, Dillavou is found tortured and murdered. Billy confronts Patti, who claims she met with Ramona to help obtain the black book. Reporter Kim Beans tells Billy that Amy has offered immunity to defendants in exchange for the ledger and that Margaret Olson is positioning herself for a mayoral run.

At the pretrial hearing, Kate provides surprise testimony fabricating probable cause for the raid, and the judge rules for the prosecution. Amy reveals the state's attorney's office has its own investigation into a protection racket at the brothel and suspects Kate is the corrupt officer. Billy surveils Kim Beans to identify the source of the weekly photographs of brothel clients, but the source never appears.

Meanwhile, Patti breaks into Amy's apartment and finds a thumb drive containing scanned images of Ramona's handwritten ledger. The final pages list monthly payoffs to a single law enforcement name: Harney. Patti assumes this refers to Billy and steals the drive to protect him, never considering the name could refer to their father.

Back in the present, the Wiz is assigned to investigate the shootings. After searching Billy's house, he finds a gun and a knife hidden in the basement: The gun matches the ballistics for Washington's murder, and the knife bears Dillavou's blood and Billy's fingerprints. Billy is arrested and charged with four counts of first-degree murder. The night before trial, Billy's father offers to help him flee to Mexico, with Goldie waiting outside; Billy refuses.

At trial, Margaret Olson prosecutes, arguing Billy raided the brownstone to steal the black book and killed four people to cover his tracks. Forensic evidence ties the weapons in Billy's basement to the murders of Dillavou and Washington. The Wiz testifies that he investigated Billy for corruption and became Amy's confidential informant. The night before Billy is to testify, an intruder breaks into his home. Billy kills the attacker, and the surge of adrenaline shatters the psychological barrier blocking his memory.

Billy takes the stand and reveals the full truth. On the night of the shootings, Amy found a copy of the ledger on a thumb drive in Margaret Olson's safe, with the name Harney on every payoff line. She confronted Billy at her apartment, holding his own gun. Kate arrived uninvited, also believing Billy was corrupt. Then Goldie entered, having listened through a bug he planted in Amy's apartment. Goldie shot Kate without hesitation and revealed that he, not Billy, was the dirty cop, working alongside Billy's father, Daniel Harney. Goldie killed Washington and Dillavou and framed Billy by planting the weapons in his basement. Daniel entered the bedroom with Kate's gun. When Billy refused to accept the cover story, Goldie shot Amy, and Daniel shot his own son. Before losing consciousness, Billy activated his phone's recording, which Patti had set to upload to a private Facebook page he shared with Stewart, an elderly friend.

The audio recording destroys the prosecution's case. Goldie cooperates with federal prosecutors and implicates Margaret Olson, who is arrested. Federal marshals find Daniel and Goldie in Playa del Carmen, Mexico, and bring them back for trial. Patti is devastated to learn their father was the Harney in the ledger. Billy returns to the Hole in the Wall, performs a comedy set, and receives a standing ovation from his fellow officers, signaling his tentative return to the force.