In a routine sweep to nab every outstanding suspect, the detectives divvy up the warrants. But when they cast their nets, they bring up far bigger fish than expected.

In the aftermath of a riot, cops are being lured into ambush shootings by a rash of bogus 911 calls. Vic and Aceveda are forced to work together to stop the attacks and solve the problems in the Grove, while Gilroy tries to pit the two against each other in an attempt to save his own job.

David works with Vic and the Strike Team to take down a dealer giving heroin to school kids, while Dutch and Claudette help a woman find her Alzheimer addled mother.

When Vic discovers that Ronnie has been burned as payback, the rest of the team does everything they can to put an end to him. Meanwhile, Claudette makes headway on her investigation against Vic after a conversation with Corrine, and Dutch takes Danny under his wing as they try to find the suspect of a Thai Town beating.

The Strike team's attempt to play by the book comes to an abrupt end when they discover that two gangs, the Byz Latz and the One-Niners are attempting to alter the balance of power by acquring MP5s. Claudette and Dutch investigate the murders and feet decapitation of 4 Armenian men by the Armenian mob in their search for the stolen cash from the money train. Meanwhile, Danny who is doing temp work at a high school while waiting for an appeal, discovers she might me be able to get her old job back.

A prostitute seeks the help of the police in her quest to bring down her pimp. Claudette assigns Vic against his wishes to the case, which puts him on the verge of going over the edge. Dutch uncovers a disturbing trend of rapes and a politician is arrested for solicitation.

Aceveda finds himself in a near fatal confrontation, and enlists Vic to help him take down the suspects in order to help service his own personal agenda. Meanwhile after losing her position of power, Claudette rejoins Dutch on the search for the cuddler rapist as they get a stunning break in the case.

When Aceveda confirms that the Strike Team is the target of an Armenian mob hit, Mackey must take matters into his own hands. Meanwhile, Whym's career is on the line when she disobeys Aceveda's orders to put a case to rest that may prove the innocence of convicted felons.

With Farmington on the brink of a gang war, Monica and Vic race to find the catalyst and stop the bloodshed, enlisting Antwon's help along the way. Still in the doghouse, Dutch decides to take action in thawing the relationship between Claudette and the D.A. Danny and Julien get up close and personal with the Farmington 1-Niners, while Monica looks to Vic for support when the implementation of her property seizure policy challenges her morality.

Vic and Monica stake a deal with the DEA to shut down Mitchell's tar heroin operation. When the bust comes up empty, Vic's suspicions of Shane grow, until Shane proves himself by coming up with a key piece of evidence that reveals a large stash of tar being stored at a local church. Meanwhile, Dutch and Claudette's friendship continues to feel strain as they try to tie a young woman's murder to a suspected serial killer. Plus, Julien takes a stand against Monica's policy, then goes to David for support when she suggests he consider transferring out of Farmington.

Monica and Vic rush to get their informants off the street after two C.I's are found brutally murdered. Meanwhile, as Dutch and Claudette investigate a brutal beating and robbery, a case from the past forces Dutch to take one in the line of duty. Plus, Vic suspects he's being set up when Shane comes to him after his situation with Antwon and Halpern spins out of control.

Vic and Monica go head to head with Antwon, and do everything in their power to get him to admit to being involved with the cop killings. Monica is shocked when Vic and Shane confront her with the information they've been hiding regarding Antwon and Angie's body. Shane and Army wonder if they'll be able to pass the lie detector test Monica is forcing them to take. Meanwhile, after another young black woman is murdered, Dutch and Claudette hope to prove their suspicions correct with their recently relocated Texan.

Monica, Vic and the strike team work together to put Antwon Mitchell back behind bars after his deal with the DEA released him from prison. When Vic reveals his suspicions of David's connection to both Antwon and an inmate's murder, David must protect his political future at any cost. When the murder of an over-protective father leads Claudette and Dutch back to a foster home they had previously investigated, Monica makes an unpopular decision that helps seal her fate.

As racial tension in the area escalates, the Strike Team attempts to end a race war, while Claudette and Dutch investigate a riot at a high school. Meanwhile, an Internal Affairs officer begins his investigation of Vic and the Strike Team by first zeroing in on Lem. A pregnant Danny refuses to reveal the identity of the father, and Julien begins training a rookie cop named Tina Hanlon.

Kavanaugh seeks the help of Antwon Mitchell in his ongoing quest to take down the Strike Team. In the midst of this, Kavanaugh has a lot on his mind as his ex-wife reenters the picture, and he reluctantly agrees to let Vic send Emolia undercover to infiltrate a Salvadoran gang that is stockpiling grenades.

As Vic prepares to help Lem get out of the country to begin a new life in Mexico; Kavanaugh and Aceveda attempt to capitalize on the situation by using this as means to try to take down the leader of the Strike Team. Dutch decides to file for a transfer. Meanwhile, Shane tries to cut off the investigation by taking extreme measures and Danny finally confronts the father of her child.

Claudette gives Vic a chance to save his job if he agrees to train his potential replacement. An unsolved rape case from the past that Dutch and Claudette were working on resurfaces. Meanwhile, Aceveda meets someone that can help him further his political career.

Claudette notices Hiatt's mistake when he makes an arrest, and Billings delivers shocking news to the department. Vic forms an alliance with Aceveda, while he waits for his review board hearing. Meanwhile, Shane's life keeps spiraling out of control.

A local priest may be protecting drug dealers; Dutch and Billings close in on attempted cop killers; Corrine learns uncomfortable truths about Vic.