Allegations against the Strike Team are front-page news, and the team is broken up pending the investigation. Vic and Claudette find themselves following the trail of a meth batch, while Shane and Dutch attempt to get along on a case.

Aceveda turns to Claudette after a double homicide raises ire and fear within an ignored community. Vic is forced to help Assistant Chief Ben Gilroy avoid being implicated in a hit-and-run, while Shane and Lem follow the trail of a gunrunner with a penchant for cockfights.

As Vic gets closer to finding his family, the Strike Team focus their attention to Armadillo after he burns down Tio's HQ. Now Vic must prevent Claudette from finding out the truth about his connection to Tio and his men. Meanwhile, Dutch is followed around by the new civilian auditor to solve a meter-maid murder, and Danny and Julien try to clear up issues between feuding neighbors.

Still fuming from the death of Tio and his brawl with Armadillo, Vic takes a day off and leaves the Strike Team with Aceveda, only to end up helping an old partner bust the man who helped him lose his job. Meanwhile, Dutch and Claudette search to find the people behind the torture and mutilation of a woman who may still be alive, and Julien fails to back up Danny's side of the story from her shooting.

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.

Vic and Emma try to help a woman who's in an abusive relationship. Vic and the Strike Team begin to make plans for the money train take down, even though the greenlight still has them on their toes. When David tells Dutch that he embarrassed the department with the Bob and Marcy case and that Claudette is now lead on all their cases, he's forced to take any action necessary to prove himself in a new homicide. Danny finally makes a stand against Yassirah.

With Ronnie's face healed he comes up with a plan to take down the Money Train, and the Strike Team is all in. Unfortunately, a federal criminal comes back to Farmington, and the Team has to use every connection trick, and resource to bring him in to prove the Barn is still a force. Meanwhile, Dutch and Claudette investigate the rape of a young girl which leads to information that puts the case in a new light. Plus, an old friend from the past reappears to make Julien's life hell.

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.

The newly arrived Decoy Squad and the Strike Team go head to head in the investigation to solve a car-jacking case. Dutch gets in over his head on an attempted murder case.

Vic struggles with Claudette's new supervision of the Strike Team. Marked bills lead Aceveda and a federal agent closer to the truth about the Armenian money-train heist in an episode with a recurring motif of people not reporting crimes against them.

Vic and the Strike Team decide to take risky measures to protect themselves from being linked to the Money Train heist. Unfortunately, their plan is interrupted when one of Vic's open cases is suddenly linked to a Narco Corrido song.

When two high profile murders are linked to each other, Aceveda orders Wyms to get the entire Barn involved before gang and racial violence breaks out. Mackey uses the case to leverage himself and the Strike Team back into the streets of Farmington.

When a mole in the treasury department is discovered and the framed suspect in the Armenian money train robbery turns up missing, the Strike team race to find the suspect before their cover is blown. Meanwhile, Claudette attempts to make amends with the Decoy Squad by going undercover to help them on a 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.

Mackey tries to help an old acquaintance find a wayward teenager, but the search quickly turns ugly when the missing teen appears to have been involved in a shoot-out. Meanwhile, Shane heads out into the field with his new partner Army, teaching him shady police tactics and seeing how far he'll go to be partnered up. Plus, Aceveda spends his last day trying to bury Vic for good, which makes things difficult for Rawling trying to take his place.

When Monica puts Vic on the trail of an escaped fugitive in Farmington, he must continue to prove his worth while playing it straight. Claudette gets suspicious of the D.A's motives when she and Dutch are assigned to investigate a major drug dealer who ends up being a minor offender. David seeks an illicit outlet for the troubling feelings caused by his rape. Vic decides to bring Shane closer as his fears about Shane's connection to Antwon Mitchell rise.

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, 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.

Via a bug planted in the clubhouse, Kavanaugh monitors the Strike Team as they investigate an illegal prescription drug ring that is proving to be deadly for the people of Farmington. While working on a missing person’s case, Dutch attempts find out what Claudette is hiding.

As the Strike Team is preoccupied with gang violence, Kavanaugh decides to make the Barn his base of operations. An evasive serial killer from Dutch and Claudette’s past reenters their life. Meanwhile, additional strain is placed on their working relationship when Tina learns something personal about Julien.

The Strike Team attempts to make bail for Lem who is now in jail, but they discover that Kavanaugh has frozen their accounts. Claudette returns to work to help Dutch investigate the murder of a man who’s body was found in the dumpster. Meanwhile, Tina jeopardizes her future at the Barn after she endangers the life of an undercover detective. Corrine confronts Danny about Vic’s unfaithfulness and the identity of the baby’s father.

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.

With the Barn grieving over the loss of one of their own, Vic's out to avenge his friend's murder, but finds himself in the crosshairs of Kavanaugh. Claudette assigns the Strike Team to investigate the torching of a methadone clinic. Meanwhile, Julien and Tina look into a robbery/assault at a porno shop, and Dutch makes a horrifying discovery in San Marcos.

Vic redirects his attention to finding out who really killed Lem after he learns for certain that Guardo wasn't involved. The Strike Team investigates the murder of a politician's daughter. Later, Cassidy confronts her father about his unethical past.

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.

Vic challenges Shane and deals with threats to his family; a federal agent arrives in Farmington to investigate a recent wave of violence.

As a local gang war heats up, Vic positions himself as a valuable commodity to the warring parties; Corrine and Cassidy confront Vic.

Vic works an angle to make himself valuable to the Armenian mob; Corrine finds herself in a surprising legal jam; Tina targets a producer of adult entertainment.

The gang war erupts in unexpected ways that Vic cannot control; Dutch and Billings' homicide investigation grows into something more disturbing; Cassidy reaches out to Danny.

Vic closes in on Shane, Mara and their sick young son; Claudette dismantles the Strike Team; Pezuela offers Acevada "assistance" for his mayoral campaign; Rita Denton (Frances Fisher) comes on to Dutch; and Billings' ex-wife and daughter are fearful when a registered sex offender moves into their neighborhood.

While Shane remains holed up in L.A. with Mara and Jackson, Corinne decides to cooperate with Dutch and Claudette, who's now spearheading the LAPD effort to bring down Vic. Meanwhile, Vic plays Aceveda, Pezuela, Beltran and ICE against each other. But Ronnie's tempted to simply give up and run to Mexico. "And you should run too man" he tells Vic.

Corrine agrees to be Vic and Shane's go-between and also agrees to cooperate with Claudette and Dutch as she does so. Meanwhile, Vic comes to an understanding with Aceveda and seeks one out with Olivia; and Claudette assigns Ronnie to work with Julian to investigate the murder of a high-school football star, keeping Ronnie out of the barn and unable to intercept the letter Shane sent to Claudette detailing the Strike Team's "sins."

Olivia joins forces with the Strike Team to catch a Mexican drug king and his shipment. Meanwhile, Dutch cleans up Billings' mess, and the death of a woman associated with the Strike Team prompts an investigation by Claudette.