Faith Mitchell, a special agent with the Georgia Bureau of Investigation (GBI), returns late from a training seminar to find her mother's house in disarray. Evelyn Mitchell, a retired Atlanta police captain who watches Faith's four-month-old daughter Emma daily, is unreachable by phone. At the house, Faith discovers a bloody handprint on the kitchen door, Emma locked in the backyard toolshed, and Evelyn's revolver missing. She calls dispatch using Code 30, the emergency signal for an officer in distress, arms herself, and enters.
Inside, the kitchen is ransacked and a dead man lies in the laundry room. In Evelyn's bedroom, Faith confronts two men: Ricardo, a member of Los Texicanos, the Mexican gang controlling Atlanta's drug trade, and Benny Choo, an enforcer for the Yellow Rebels, a rival Asian gang, holding Evelyn's revolver to Ricardo's head. Choo offers to trade Evelyn for whatever the intruders seek. Faith feigns agreement, tosses her shotgun as a distraction, and shoots Choo. Ricardo flees into a neighbor's backyard where two children are playing and fires toward them; Faith kills him. Before dying, Ricardo whispers: "Almeja." Three men are dead, Emma is freed, and Evelyn is gone.
Dr. Sara Linton, a pediatric attending at Grady Hospital whose police chief husband was killed years earlier, meets Will Trent, Faith's GBI partner, at a restaurant. Sara is drawn to Will, a guarded agent who grew up in foster care and hides severe dyslexia. Their connection is cut short when Will's boss, Deputy Director Amanda Wagner, summons him to the crime scene. Sara takes Will's Chihuahua, Betty, to his house, where Will's wife, Angie Trent, confronts and threatens her.
At the scene, Will faces hostility from officers who resent his earlier investigation of Evelyn's narcotics squad, which sent six detectives to prison for skimming roughly six million dollars from drug busts. Evelyn retired with her pension when the prosecutor declined to charge her. Sara arrives at Will's request and diagnoses Faith with a severe insulin reaction from recently diagnosed diabetes. After treatment, Faith gives a clear account. Amanda translates "Almeja" as slang for money, suggesting the intruders wanted cash.
Will and Amanda find a dead man in the trunk of Evelyn's car: an older Hispanic man with a Los Texicanos tattoo. Evelyn's neighbor, Roz Levy, a retired crime scene photographer in her eighties, identifies him as a frequent visitor she has been secretly photographing. The crime scene reveals Evelyn was duct-taped to a chair; Will finds a blood-drawn symbol underneath it that Amanda signals him to conceal.
Amanda takes Will to death row to visit Boyd Spivey, the former lead detective from Evelyn's squad, who insists Evelyn was protected and directs them to contact "Ling-Ling" in the Asian gang world. Minutes later, Boyd is killed in the corridor; the security camera had been disabled the day before. The murder gives the GBI jurisdiction.
Faith returns home to find her brother Zeke, an Air Force surgeon she did not know was stateside. That night, she discovers a Facebook message on her son Jeremy's account warning her to "keep your mouth shut and your eyes open" (158-159). Beneath her pillow, she finds her mother's severed ring finger, placed there while police sat in her kitchen. Terrified by escalating signs that the intruders are monitoring her home, Faith sends Jeremy, Zeke, and Emma to a military base.
Will brings case files to Sara's apartment for her help reading them. They identify the trunk victim as Hector Ortiz, cousin of the imprisoned Los Texicanos leader. Sara corrects Amanda's translation: "Almeja" is a vulgar insult that also served as Evelyn's street nickname. Amanda's investigation reveals that Chuck Finn, one of Evelyn's former detectives, overlapped at a Tennessee rehab facility with Hironobu Kwon, the dead man from the laundry room. The theory crystallizes: Chuck shared the story of Evelyn's supposed hidden money, and Kwon recruited Ricardo and others from a cabinet shop run by Julia "Ling-Ling" Ling, the outside boss of an Asian gang called the Yellow Rebels.
Amanda and Will visit Julia, who confirms the young men acted without authorization, but workers open fire as they leave. At Grady Hospital, Sara finds Marcellus Estevez, a gravely wounded Los Texicanos gang member whose fingerprints place him at the scene of the break-in at Evelyn's house. A gunman kills Estevez and turns on Sara; she slashes his thigh with a scalpel, severing his femoral artery, and the attacker kills himself. Amanda has withheld news of Sara's attack from Will during the warehouse shootout, and Will is furious.
Will speaks with Roger Ling, Julia's imprisoned brother and the gang's true leader. Roger helps reconstruct the conspiracy and confirms no grudge against Faith, then whispers that Evelyn is dead. Will delivers the news to Amanda, who buckles against him. That night, Will's confrontation with Angie escalates until she puts his unloaded gun in her mouth. Will tells her he would rather be alone, then drives to Sara's apartment. They spend the night together.
Monday morning, Faith arrives with proof Evelyn is alive: a video showing her holding that day's newspaper. Faith reveals that a young Hispanic man with blue eyes confronted her in a grocery store bathroom, threatening to kill her children if she told anyone. The kidnappers demand cash at Evelyn's house. Amanda insists on the exchange, deploying undercover agents and positioning Will as a sniper in Roz Levy's carport.
Two men deliver Evelyn to the house, using her as a shield. Faith enters with a duffel bag of tracked bills and finds the blue-eyed man aiming a Tec-9 semiautomatic at her mother. He kills his own partner, then reveals himself as Caleb, Evelyn's biological son by Hector Ortiz. Evelyn became pregnant during an affair with Hector, her confidential informant. Faith's father, Bill Mitchell, refused to accept a mixed-race child, and Amanda arranged an adoption. Caleb grew up unaware of his origins until his adoptive mother's medical crisis revealed the truth, and he channeled his rage at the mother who kept Faith and Jeremy but abandoned him.
Faith communicates positions to Will by phone using military time. Will does not understand the code, but Roz Levy, eavesdropping with a revolver, decodes it. Amanda fires through the curtains, hitting Caleb's shoulder. As he swings the Tec-9 toward Faith, Evelyn grabs a fallen Glock and shoots her son twice in the head, killing him to save her daughter. Faith crawls to her mother, who whispers, "Everything's going to be all right" (427).
Three days later, Evelyn tells Will the full truth from her hospital bed. A secret bank account held in her late husband's name, which Will had identified as suspicious during his earlier corruption investigation, held monthly support payments for Caleb, not stolen money. She was the anonymous tipster who turned in her own squad; the detectives nicknamed her "Almeja." She tells Will that Amanda considers him like a son. When he asks if Amanda is his actual mother, Amanda laughs so hard she braces against the wall.
Sara, finding threatening notes from Angie on her car, tells Will she cannot be with him while he wears his wedding ring. Will explains the origin of the scar on his arm: As a child, he deliberately cut himself to force an investigation that shut down a foster home where Angie was being sexually abused. He accepts Sara's decision and turns to leave. Sara realizes Will has spent his life expecting abandonment and needs someone to fight for him. She chases him to the elevator, asks if he wants to be with her, and when he answers yes, tells him she changed her mind and asks him to kiss her.