Erin O'Reilly Mysteries Books in Order

NYPD officer Erin O'Reilly and her K-9 partner Rolf move to day shift just as an art theft at the Queens Museum turns deadly. Chasing the killers across New York, Erin stumbles into old secrets and much bigger trouble.

Erin juggles two ugly cases at once, murdered Scottish gangsters and a woman posed in a locked hotel room. As mob tensions rise, she starts to suspect a clever killer may be watching her too.

On her first day as a detective, Erin and Rolf investigate a car bombing tied to gamblers, mobsters, and former IRA men. The case pits an Irish cop against the Irish mob before another blast can hit.

Erin and Rolf look into a motel-room double murder that points straight at the Russian Mafia. The trail leads into Little Odessa, human trafficking, and a brutally dangerous criminal network.

A woman dies onstage during a Broadway magic show on New Year's Eve, and Erin suspects murder instead of accident. While she untangles the trick, her growing attraction to gangster Morton Carlyle threatens to complicate everything.

A dentist dies after eating tainted Valentine's chocolate, giving Erin and Rolf a case full of secrets, grudges, and romantic chaos. At the same time, Erin's connection to Carlyle pulls business and pleasure into dangerous overlap.

A call of officer down sends Erin and Rolf racing above and below New York City after a cop killer. With terrorists, hitmen, and rumors of a dirty cop closing in, saving Manhattan becomes painfully personal.

A young woman is strangled in her apartment, and Erin, Rolf, and Major Crimes must sort jealousy from robbery and serial violence. Meanwhile, Erin's romance with Carlyle reaches a point where trust becomes a real risk.

Erin returns from vacation to a home-invasion double murder and discovers some wounds do not stay buried. As she tracks the killers, old trauma and the scars of violence start pressing in from every side.

A brutal mob hit leaves Erin and Rolf following leads that brush against Morton Carlyle's world. As gangland loyalties splinter and bodies pile up, Erin has to decide how far she can go for the people she loves.

A body in a luxury hotel turns stranger still when Erin finds a young woman floating in the building's aquarium. To solve it, she and Rolf have to dive into bribes, voyeurism, and Erin's own dangerous double life.

What looks like a simple home-invasion shooting turns uglier when the only witness is Lieutenant Webb's ex-wife. Erin and Rolf dig through property scams, attack dogs, and Brooklyn street crime while Webb's past threatens the case.

After a deadly ambush leaves Carlyle fighting for his life, Erin is distrusted by both cops and gangsters. An undercover assignment and a fresh murder force her to navigate lies, shifting loyalties, and very personal consequences.

A frightened young woman leads Erin to a dead man in a parked car, but the case quickly tangles with politics and mob business. Erin and Rolf must link a supposed overdose to deeper corruption and possible assassination.

A courthouse shooting and the murder of a young woman pull Erin into Mafia family politics from two sides at once. Protecting a gangster's son and coaxing a terrified witness into speaking both come with real danger.

Erin wakes in a notorious playboy's apartment with a hangover, a new tattoo, and missing hours, just as Manhattan loses power. A false confession and a citywide blackout send her and Rolf hunting a psychopath in the dark.

A waiter murders a diner in an Italian restaurant, but that killing is only the first shot in a bigger Mafia purge. Erin and Rolf are pulled into a brutal struggle over power, justice, and the blurry line between them.

Erin's fake reputation as a dirty cop keeps her close to the Irish mob, until a failed car bombing turns her into open prey. When the violence spills toward her family, she and Rolf face one of their most personal fights yet.

A drug bust in Little Italy ends with plainclothes cops shooting at each other and one of Erin's friends dead. Sidelined officially, Erin, Rolf, and her allies dig into crooked cops, Mafia dealers, and a cover-up.

Erin is close to helping bring down the Irish mob when a construction crew uncovers three bodies from an old Brooklyn turf war. Digging into the cold case draws her and Rolf toward a secret worth killing for.

A playboy's pilotless plane crashes in Brooklyn with cocaine on board, and his body turns up days later. Erin and Rolf step into a vicious scramble among mobsters, cartel men, and law enforcement over money, drugs, and survival.

Erin is already risking her life undercover when a trap-setting assassin starts targeting New York judges. As she and Major Crimes race to stop him, old mob grudges keep making a bad situation worse.

Still dealing with the aftermath of the last case, Erin investigates the skull-crushing murder of a former convict turned pizza driver. Her mind is not at full strength, which makes every lead and every choice more dangerous.

Erin is poised to help finish off the O'Malley gang in the early hours after Christmas, then the whole operation falls apart. Informants are shot, buildings burn, and she and Rolf race through Manhattan to salvage the bust.

A freak Manhattan blizzard turns Erin's undercover life into a trap when Evan O'Malley starts hunting for the police mole in his crew. With missing allies, dead cops, and a possible traitor in the NYPD, the storm closes fast.

Back from a long break and newly engaged, Erin expects an easier return than a dead cop in a bar. The apparent suicide opens into a puzzle trail that hints at hidden enemies inside the NYPD.

Erin hunts a vigilante killer who seems determined to eliminate men the law never quite touched. As the bodies pile up, the case forces her to weigh justice, revenge, and an old enemy moving in the background.

When an assassin massacres Richie O'Malley's family with Erin's own gun, she goes from investigator to prime suspect in a heartbeat. Suspended and under siege, she and Rolf must clear her name before a hidden enemy closes the trap.

A stabbing in the Rikers infirmary exposes a power struggle among inmates, crooked corrections officers, and Mafia leftovers. Erin and Rolf fight violence on both sides, while a hard-charging Internal Affairs lieutenant threatens her own house.

Erin becomes front-page news after taking down two crime families, just as a serial killer begins hunting young women across New York. Solving the case means racing the clock, the press, and the city's appetite for spectacle.