Kacey overdoses at age 16; Mickey tracks her to a drug house and paramedics revive her.

Mickey begins a romantic relationship with police officer Simon after turning to him for comfort.

Kacey moves into Mickey's house after her release from prison and stays clean for six months.

Mickey finds drug paraphernalia hidden in Kacey's room and Kacey silently packs up and leaves.

Mickey discovers Kacey is pregnant with Simon's child and takes legal custody of the newborn Thomas.

Mickey and rookie partner Lafferty discover a dead woman in Kensington; Mickey suspects she was strangled.

Detective Nguyen announces at roll call that a serial killer has been strangling women in Kensington.

Mickey learns from a convenience store owner that Kacey has been missing from her usual corner for a month.

A prostitute named Paula tells Mickey that the suspect caught on surveillance footage is a cop.

Internal Affairs suspends Mickey for using police databases and conducting a personal investigation while on duty.

Mickey finds hidden letters and money from her long-lost father under a floorboard in Gee's house.

Mickey tracks down her biological father and discovers Kacey has been staying with him during her pregnancy.

Paula is found strangled; detectives warn Mickey she may be the killer's next target.

Mickey corners Lafferty in an abandoned cathedral, and Dock retrieves her gun so she can subdue him.

Mickey resigns from the police force and anonymously tips off a reporter; Kacey gives birth to a healthy daughter.

Mickey Fitzpatrick is a Philadelphia police officer whose estrangement from her drug-addicted sister Kacey was caused by Kacey's affair with Mickey's boyfriend Simon and the birth of their son Thomas. In the present, Mickey's investigation of a murdered woman in Kensington expands into a serial killer case just as she discovers Kacey has gone missing. A tip from a local prostitute named Paula points Mickey toward a corrupt cop as the killer, but she is suspended before she can act on it. A confrontation with her grandmother Gee leads Mickey to her long-lost father, who reveals where Kacey has been hiding during her pregnancy. The sisters reunite and work together to corner Mickey's own rookie partner Lafferty as the serial killer. After the arrest, Mickey resigns from the force and exposes departmental corruption, while Kacey gives birth to a healthy baby daughter.

The headline events of Mickey's investigation and the sisters' fractured past.

Mickey and Kacey's mother dies of a drug overdose, and their father is eventually driven away by Gee.

Mickey and Kacey attend a Nutcracker performance with their class and are ejected after Kacey causes a scene.

Gee refuses to fill out financial aid forms, destroying Mickey's chance of attending college.

Kacey is arrested for robbery and sentenced to a year at Riverside Correctional Facility.

Mickey visits Kacey at Riverside Correctional Facility and the two sisters begin to reconnect.

Thomas is born addicted to heroin and Mickey nurses him through a painful withdrawal.

Mickey questions Sergeant Ahearn about the dead woman found in Kensington; he dismisses her concerns.

Mickey violates police protocol by searching Kacey's arrest record and tracing her new boyfriend Dock on Facebook.

Mickey and Thomas attend Thanksgiving at Cousin Ashley's house; relatives warn her that Dock is dangerous.

Truman infiltrates Dock's house posing as a junkie and discovers a photograph of Kacey among Dock's prostitutes.

Mickey breaks into Dock's house to search for Kacey; Dock catches her and threatens her son Thomas by name.

Simon walks into Thomas's birthday party with his new wife and baby and refuses to acknowledge the boy.

Mickey visits Truman at home after her suspension and he suggests Simon might be the serial killer.

Kacey tells Mickey she was born addicted to heroin, unlike Mickey, reframing the story of their different fates.

Mickey and Kacey research Lafferty online together, and Kacey immediately identifies him as a friend of Dock's.

The sisters' troubled history begins with the death of their mother and their father's forced absence, leaving them in the care of a cold and resentful grandmother named Gee. Kacey's drift into addiction is shaped by her environment, while Mickey's ambitions are actively undermined by Gee's refusal to support her college dreams. In the present, Mickey bends and breaks police rules to investigate Kacey's disappearance, checking records, attending family gatherings, and following leads about the dangerous Dock. Her inquiries grow more dangerous as she and Truman infiltrate Dock's world, and she endures personal humiliation when Simon coldly ignores his own son at a birthday party. A key revelation arrives when Kacey discloses that she was born addicted to heroin, fundamentally reframing the sisters' lifelong argument about who had it harder. The pool ends with the sisters joining forces to unmask Lafferty, using Kacey's street-level knowledge to confirm what Mickey had suspected.

The secondary events and backstory that shaped the sisters' diverging lives.

Mickey and Kacey join the Police Athletic League; Mickey becomes strongly attached to the officer Simon Cleare.

On Simon's advice, Mickey enrolls in the police academy and begins her career in law enforcement.

After Mickey cuts off Kacey's access to Thomas, the two sisters stop speaking entirely for five years.

Mickey's partner Truman is beaten with a baseball bat by a masked assailant who then draws a gun on Mickey.

Neighbor Mrs. Mahon tells Mickey that a man came to the apartment looking for her new address.

Detective Nguyen shows patrol officers surveillance footage of a hooded figure following one of the strangulation victims.

Truman tells Mickey he is quitting the police force because too much power is in the wrong hands.

Detective DiPaolo tells Mickey at a bar that a local man named Mulvey has just been arrested for the killings.

Mickey makes a drunken pass at Truman after her theories are dismissed by DiPaolo; he gently turns her down.

Mickey calls 911 in a panic when Thomas vanishes without explanation, fearing someone has taken him.

Mrs. Mahon reveals she is a former nun, and Mickey tells her the full story of her life over dinner.

Mickey visits Gee on Christmas and discovers that someone broke in through the alley door months earlier.

Mickey follows Truman to an abandoned building and discovers he has been secretly supplying addicts with food and medicine.

Kacey reveals she deliberately set Dock against Lafferty and tipped off the detectives to arrange the cathedral confrontation.

Mickey apologizes to Kacey for the pain she caused over the years, and the sisters begin to genuinely heal.

The novel's emotional stakes are set in motion when a teenage Mickey becomes attached to Simon Cleare at the Police Athletic League, a choice that shapes both her career and her most destructive relationships. Years of unspoken grief harden into a five-year silence between the sisters after Mickey severs Kacey's contact with Thomas, and a violent assault on Mickey's partner Truman casts a long shadow over the present-day investigation. A series of destabilizing events — a neighbor's warning, a disputed arrest, a drunken confession, and Thomas's brief disappearance — strips away Mickey's certainty about who she can trust on the force. A defining turn comes when Mickey realizes Truman, briefly suspected as the killer, is actually the most principled person in her life. The investigation climaxes when Kacey executes a bold plan to trap Lafferty in a cathedral, revealing her as not merely a victim but an active force in her own story. The pool closes with Mickey taking responsibility for the past and the two sisters finally beginning to heal.

The pivotal decisions, discoveries, and emotional shifts that reshape the story.