Harlee refuses to give Stahl incriminating evidence against Wozniak but hands over a fully resolved unoffical investigation that Tess and Espara initiated when they moved a body by Tess' house found to be murdered with a 3D printed gun. Wozniak confronts Harlee who executes a dangerous bluff.

Loman's guilt over the death of an unarmed suspect becomes a liability for the crew, forcing them to test his loyalty. Wozniak sends Harlee on an errand that reveals he has a silent partner in the big score. Wozniak realizes Donny has been withholding information. Harlee feigns cooperation with Stahl, but unwittingly leads the FBI to incrimmating evidence,

Harlee and Tess intercept a heroin shipment from a local drug lord who discovers Wozniak's secret and tries to use it as leverage to get his confiscated drugs back. Harlee fears Stahl's interest in her goes beyond the professional, believing he is invading her privacy, and resorts to spying on him with the help of an old friend. Tess tries to use Espada to get back at her husband.

Wozniak's suspicions land on Saperstein, forcing Harlee to convince Stahl to arrest Saperstein in order to keep him safe. Harlee visits her abusive ex, Miguel, who tasks her with tracking down the man who committed the murder for which he is imprisoned.

After Saperstein's death, Harlee realizes there are no lines Wozniak won't cross and decides to help Stahl's investigation. The crew retaliates against a pair of abusive cops after they harass Harlee's daughter Cristina and her boyfriend. Wozniak makes Loman feel like a part of the unit.

Harlee and Wozniak secure more details on the big score and meet Donnie's silent partner, who reveals himself to be an DEA agent.  They learn the big score is an armored car heist.  Wozniak takes interest in a fellow marine veteran who is suspected of murder under dubious circumstances.

Harlee and Wozniak attempt to deal with the consequences of the heist's money disappearance. Harlee informs the FBI that she will get the money back.

Harlee and Wozniak investigate Caroline's murder, putting Harlee and Nava's relationship in an awkward place because she can't reveal her connection to the crime or the methods she will use to solve it. Wozniak focuses on determining which member of his crew is informing to Verco as Loman uncovers a much deeper secret.

Harlee makes the chilling discovery that someone is texting Cristina as her dead ex, "Miguel." The case of a missing kid leads Wozniak to uncover a local dealer who uses underage mules and reminds Loman of what their unit is all about. The crew gets caught in a brutal ambush.

Harlee and Wozniak, still dealing with the fallout from their near death experiences, discover a grisly crime scene riddled with mystery.

Harlee discovers that the intelligence unit’s involvement in criminal enterprises goes deeper than she thought. Ramsey strikes back. Tufo pulls away from the crew. Loman meets a girl.