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 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.

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.

Harlee Santos, a detective from a tight-knit group of Brooklyn cops with questionable tactics, is arrested by an FBI agent who wants to make her an informant. Co-stars Ray Liotta.

Harlee struggles with becoming an FBI informant while Wozniak suspects every member of his crew. Paranoid that Wozniak's search will lead to her, Harlee suggests polygraphng the entire crew, a plan that backfires. An appeals case sends Wozniak to watch tapes from his first encounter with Harlee, revealing a dark secret from their past. Meanwhile, Espada helps Tess deal with her husband's infidelity.

Harlee focuses her sights on taking down the intelligence unit. Stahl’s continued obsession brings him closer to New York. Wozniak uses Wallace as Espada struggles with keeping secrets from Tufo.

Dealing with a loss, Harlee pursues evidence of a higher level of corruption within the NYPD. Wozniak tries to protect Harlee and his crew from escalating threats.

Harlee questions her own sanity as Wozniak keeps secrets from those closest to him. Loman intimidates a witness.

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.

Following Harlee's brave confession to the entire crew that she has been informing for the FBI, the team grapples with Harlee and Wozniak's betrayal. With their team falling apart, Harlee and Wozniak come up with a desperate plan to neutralize Bianchi. However, their actions have unforeseen consequences because the Mafia fires back.

Harlee and Wozniak try to link the intelligence unit to the cartel while facing the consequences of breaking the blue wall.

Harlee fights a frame job as Wozniak tries to keep Bennett behind bars.

Wozniak finds it hard to deal with guilt as he attempts to deal with an unfinished task. Harlee needs to protect Saperstein whilst holding the unit together.

Harlee's collaboration with Stahl (Warren Kole) uncovers Wozniak's secret relationship with Donnie.  Wozniak decides to take charge of the big job after picking up a package that turns out to be a kidnapped man.  A mysterious call to Saperstein's desk forces the crew to face their mixed feelings about their fallen friend and ultimately decide to preserve his memory.

Realizing that Stahl will stop at nothing to arrest Julia Ayre, Harlee decides to investigate on her own and determine whether there's any truth in his allegations of Ayers active business with the mob. Wozniak is confronted with a drug case that forces him to face the darkest demons from his past, his daughter's death, while exposing the origin of his loyalty.

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.

Harlee faces a police commission as Wozniak and the crew scramble to help her from the outside.

Harlee Santos takes drastic measures to cover up the murder of her abusive ex, Miguel. Lieutenant Matt Wozniak makes a deal with FBI Agent Robert Stahl to keep himself and his crew out of jail but soon discovers Stahl has led him into an impossible trap. As the crew deals with the fall-out from the failed heist, Tess struggles to keep her painful gunshot wound under wraps.

The mafia seeks revenge on Harlee by framing her for murder. As Harlee works against the clock and her own crew to cover her tracks as Wozniak fights to keep his cop family together when evidence of an old crime puts pressure on the already splintering team. Stahl cozies up to Cristina getting one step closer to the truth about Miguel.

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

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.

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.

After Wozniak refuses to play ball with the FBI, Stahl turns up the heat on Harlee who lands in the middle of Wozniak's dangerous plan to free himself from the Feds by reeling in a bigger fish. Meanwhile, Internal Affairs Officer Verco applies pressure to each member of the crew to discover what really happened to Donnie Pomp.

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.