Politically ambitious new LAPD captain David Aceveda tries to crack corruption in Los Angeles' Farmington District by recruiting detective Terry Crowley to help him take down fellow detective Vic Mackey, leader of the Farmington precinct's Strike Team. As Vic and the Strike Team prepare for a dangerous night mission, detectives Holland "Dutch" Wagenbach and Claudette Wyms investigate a woman's murder, only to discover that her missing daughter has been sold off by the daughter's drug-addicted father to a child molester.

Following the murder of Terry, the Internal Affairs Division begins an investigation into his death, while Aceveda begins his own. Meanwhile, Dutch and Claudette investigate the shooting of a churro vendor that ends in the Barn's detectives busting up a gang initiation.

In a routine sweep, the Barn's detectives divvy up warrants. But when they cast their nets, they bring up far bigger fish than expected. While Vic holds a basketball star hostage to influence the outcome of an upcoming game, Dutch and Claudette nab an egotistical rapist out to impregnate as many women as possible.

Vic attempts to broker a peace agreement between two rival rappers after a dispute over an up-and-coming singer's success erupts in a gang war. Danny is attacked after identifying a shooter, Julien helps a woman whose son's body has been stolen, and Dutch and Claudette search for a missing migrant worker.

After a bust on an Armenian gang's drug delivery, Julien sees the Strike Team take a portion of the drugs for themselves. Subsequently, the vehicle holding the drugs is stolen on Shane's watch, forcing Vic to track them down before Aceveda is able to pin the theft on him.

When the body of a young hooker is found in the district, Dutch's theory about a serial killer preying on prostitutes proves true. Aceveda launches an all-out effort to find the killer before he strikes again, giving Dutch and Claudette the full resources of the Barn for 24 hours and the help of the FBI.

Vic's relationship with Shane becomes even more complicated when the pair team up with a detective from another precinct to investigate the murder of several gang member. Meanwhile, Dutch and Claudette bring in a psychic on a complaint from the son of one of her clients.

Allegations against the Strike Team are front-page news, and the team is reassigned pending the investigation. Vic and Claudette find themselves following the trail of a deadly meth batch, while Shane and Dutch team up to investigate the unsolved murder of a widow's husband.

A planted gun in a truck-jacking case causes complications for the Strike Team, and Lem attempts to set things right. Meanwhile, the rift between Danny and Julien deepens, causing Aceveda to intervene, and Claudette deals with the mess of her family during a visit from her father and daughter.

As Dutch uncovers a lead to the serial killer, a reporter's questions force Aceveda to explain problems he thought were buried fair in the past, while Vic assists Connie as she tries to quit crack cold-turkey in a desperate attempt to keep her son, leaving the other Strike Team members to investigate a strip-club mugging ring on their own.

Vic and the Strike Team mediate a dispute between Rondell Robinson and the Nation of Islam, while Dutch and Claudette investigate a brutal home invasion in the district's Korean community.

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

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 attempts to pit the two against each other in an effort to save his own job.

While Vic continues his search for Corrine and their children, the Strike Team allow more drugs into Farmington through a corrupt connection. But when their latest shipment turns bad, they head to Tijuana to uncover the culprit behind the poisoned cocaine. Meanwhile, Dutch and Claudette try to track down the man responsible for "fire-necklacing" the leaders of two separate gangs.

As Vic gets closer to finding his family, the Strike Team focus their attention to Armadillo after he burns down Tio's business, an act that threatens to expose Vic's protection racket. As Claudette gets closer to the truth about Vic's connection to Tio, Dutch is accompanied by the civilian auditor to solve the murder of a meter maid, while Danny and Julien intervene between two feuding neighbors.

Still fuming from the murder of Tio and his brawl with Armadillo, Vic takes a day off to reconnect with his old partner, and soon sets out to help him get revenge against the thug whose complaint forced him into retirement. Meanwhile, an amputated arm sends Dutch and Claudette in search of the sadomasochistic criminal behind the torture and mutilation of a woman who may still be alive, and tensions brew between Danny and Julien after Julien fails to back up Danny's side of the shooting to IAD.

Now that Vic is back to work, he and Shane go undercover as dirty cops to find the man behind a robbery and murder. Dutch and Claudette track down an old rival of Claudette's after a turned-in gun is found connected to an unsolved case, while Aceveda assigns Julien and Danny to watch over a Korean parish in an attempt to secure the Asian vote in the election.

Grade school heroin dealing prompts Vic to increase his efforts to bring down Armadillo, while Dutch and Claudette help a woman track down her Alzheimer's-addled mother.

The Barn mobilizes to investigate a massacre at a women's shelter, while Aceveda spends a day on the streets with Julien as the pair attempt to recover a child's stolen bicycle.

Vic and the Strike Team begin to prepare for the money train takedown, even though Armadillo's greenlight still has them on their toes. After embarrassing the department with the Bob and Marcy case, Dutch is forced to take any action necessary to prove himself in a new homicide, while Vic sets out to stop the abuse of a neighbor by her violent boyfriend, and Danny finally makes a stand against Yassirah.

When Vic discovers that Ronnie has been burned as payback, the rest of the team set their sights on taking Armadillo off the streets for good. Meanwhile, Claudette makes headway on her investigation into Vic after a conversation with Corrine, and Dutch takes Danny under his wing as they attempt to track down the suspect of a Thai Town beating.

Flashback to the first day of the Barn. Under pressure to get results, Vic and the newly-formed Strike Team make an impression on the streets. Dutch and Claudette realize they make a good team, and Aceveda discovers he doesn't have as much power as he thought he would.

When Lanie's report on the Barn is leaked to the press early, everyone fears the prospect of losing their jobs, including Aceveda, who's mentioned as the reason for most of the precinct's problems. Meanwhile, Gilroy skips bail and winds up on Vic's doorstep looking for help, forcing Vic and Shane to deal with him while Lem shows Strike Team newcomer Tavon the ropes; and Claudette faces some of her own demons as she and Dutch try to uncover the culprit behind a possible robbery/homicide, while Danny comes to a startling realization.

With Ronnie's face healed, he comes up with an improved 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 and resource to bring him in before Lanie submits her final report. Meanwhile, Dutch and Claudette investigate the rape of a young girl, and an old friend from the past reappears to make Julien's life hell.

While the Strike Team puts the finishing touches on the money train takedown, Vic works with Dutch and Claudette to find a missing child, while David gets an unwanted visit from the Chief and Julien is harassed by some of the other officers after Tomas outs him in front of them.

When a gang execution hits close to home for Claudette, Vic, Tavon, and Dutch work together to find the culprit before anyone else gets hurt. Shane, Lem, and Ronnie are forced to choose between hitting the money train without Vic or letting it go. As Aceveda prepares for the city council election, Danny receives some life-changing news, and the harassment inflicted upon Julien reaches a whole new level.

The Strike Team's attempt to play by the book comes to an abrupt end when they discover that the Byz Latz and the One-Niners are attempting to alter the balance of power by acquiring MP5s. Meanwhile, Claudette and Dutch investigate the murders and foot severance of Armenian men by the Armenian mob, a case that draws them closer to the truth behind the money train robbery.

Vic decides to use some of the money train robbery cash during a gun-running sting operation, but after it goes awry, tension within the Strike Team begins to mount as its members attempt to rectify Vic's mistake. Meanwhile, Dutch and Claudette seek the help of a college student named Esteban who was the only survivor in the murder of two Latino gang members.

A prostitute and friend to the late Connie named Farrah seeks the help of Vic in an effort to bring down her pimp. After failing to convince Vic to help her, Farrah goes to Claudette, who assigns Vic to the case against his wishes. Meanwhile, Dutch investigates the rape of an elderly woman.

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.

When the ex-wife and child of Julien's former partner, Tommy, are murdered, Tommy becomes a suspect, prompting Julien to team up with Mackey to conduct their own investigation. Elsewhere, Shane goes undercover to catch a group attacking gay prostitutes, and Claudette and Dutch investigate a rape case against Aceveda's orders.

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.

An oversight puts Waylon and Trish in serious danger during an undercover job and Claudette is to blame. Meanwhile, Tommy makes a drastic decision when he realizes nobody in the Barn can help him get back on the job.

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.

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.

During a routine bust on bangers, Vic and the Team discover a money laundering ring that reaches far and wide in the crime community. Meanwhile, Dutch takes the chilling confession of the man who was arrested in the serial-rape case, and Danny goes undercover.

When Aceveda assigns The Strike Team to serve a high risk warrant against a mob killer to service his political agenda, they find themselves embroiled in a hostile struggle with the Korean community. Now the Team must find out how to put an end to the situation before they end up casualties of a racial fued. Meanwhile, one of Vic's informants works with Danny on finding stolen chairs, while having eyes for her.

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.

With an Armenian hit-man hot on their trail, the Strike team sweeps the streets of the Armenian community to find him before he finds them. After catching a break, Aceveda's suspicions grow about the Strike Team's involvement with the Money Train robbery. Meanwhile, Dutch and Claudette investigate a case that could repeal hundreds of convictions, which leaves Claudette having to choose between her conscience and her career.

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.

Vic is no longer the cop he used to be, acting adrift after his past actions have caught up to him. The strike team has been dissolved, leaving Mackey to menial busts that keep him off the streets. When Aceveda moves on to his new City Council position, Captain Monica Rawling takes over the Barn and empowers Vic to implement her controversial anti-gang policies.

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.

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.

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.

A tip from Lemonhead's juvie would leads Vic and Monica to take down a major heroin operation with connections to Antwon Mitchell. Monica continues to battle Aceveda as she tries to sell her new policies to the community, and Julien begins to doubt her methods. Claudette loses trust in Dutch when she suspects he made a backroom deal with the D.A. And Shane and Army find themselves over their heads with Antwon when he blames them for Vic's heroin bust.

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.

Just as Monica and Vic get close to a big break in the Garage Sting, Chief Phillips unexpectedly hands over the bust to the Organized Crime Unit. He blames the decision on an emerging PR scandal involving a videotape of Vic at the church bust that was leaked to the Assistant Chief through Aceveda's office. Vic uses his leverage with the Byz Lats to find a Russian mob leader before the mobster flees the country. Monica threatens two foster care social workers with jail after a young girl is found close to death in her foster home, then tells Julien if he doesn't put in for a transfer, she'll request one for him herself.

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.

Monica orders her units to turn the streets of Farmington inside-out when two officers mysteriously disappear after answering a 911 call. Shane tries to make amends with his old crew after Vic agrees to help him get out from under Antwon, but things don't work out as planned. Dutch and Claudette convince Monica to let them take active roles in the case of the missing officers, but soon find themselves at a dead end with the only witness being clinically insane.

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.

Vic and the Strike Team use their leverage on the One-Niners to track down anyone involved with the cop killings. Their hunt leads them down an unexpected path with the Russian mob. Monica puts pressure on the team to come clean about any of their dealings with Antwon. Dutch and Claudette investigate a gang shooting and soon realize their key witness is close to the Barn, and has something to hide.

Vic and his crew track down the Russian who was involved with the cop murders, but they lose control during his interrogation and the hit man dies in an explosion before they can get any answers. Meanwhile, Aceveda is blackmailed by the man who assaulted him. Plus, Rawling's seizure is on the verge of being shelved.

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.

During an interrogation, Kavanaugh reviews the Strike Team’s corrupt past and attempts to weaken Lem’s loyalty to Vic by bringing up the connection to Terry’s murder. Meanwhile, the Strike Team investigates a multiple homicide. Dutch and Claudette suspect that a minister might have been involved in an attempted murder. Tina gets in over her head while on duty with Julien.

The Strike Team tries to develop a strategy to deflect the Internal Affairs investigation as Vic finally comes face to face with Kavanaugh. Meanwhile, Tina goes undercover to help take down a sex-trafficking ring; and friction between Claudette and Dutch deepens when she reopens one of their past cases.

With the IAD investigation in full force, Vic seeks legal representation from Becca Doyle for the Strike Team. Also, a suspicious Vic decides to confront Emolia after he begins to doubt her loyalty to him. Meanwhile, Dutch and Claudette investigate the ghastly murder of a pregnant woman. Tina continues to make mistakes while on duty.

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.

Claudette further aggravates her illness as she continues to aggressively interrogate Kleavon Gardner. The Strike Team works with the Chief of a citywide task force to investigate the murder of a drug dealer’s girlfriend and her daughter. Meanwhile, Kavanaugh attempts to discover how Vic acquired the $65,000 that was given to Corrine, and Ronnie is up next for questioning in the IAD investigation.

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.

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.

To the dismay of his friends, a weary Lem is thinking about accepting a deal from the D.A. where he has to plead guilty to the heroin charges. With no other choice, Vic reluctantly meets with Antwon in order to ensure Lem’s safety in prison. Meanwhile, unforeseen circumstances that are beyond Claudette and Dutch’s control might cause irrevocable damage to their friendship.

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.

Kavanaugh acquires what he needs in order to apprehend Vic who is preoccupied with getting revenge on Guardo. Claudette finds herself under the political microscope as a result of the San Marcos incident, and Danny receives some news about her future at the Barn.

Consumed by bloodlust, Vic finally gets the chance to avenge his friend's murder, despite Shane's pleas against it. Meanwhile, Ronnie is assigned by Claudette to help Dutch and Billings investigate a robbery homicide at a pharmacy.

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.

After being badly beaten, Shane's life spirals even more out of control as his guilt continues to eat away at him and his marriage begins to fall apart. Vic and Ronnie try to learn who was responsible for Shane's attack. Meanwhile, under the new leadership of Kevin Hiatt, Claudette assigns the Strike Team to investigate the San Marcos murders. Dutch and Billings make progress in a serial rapist case.

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.

After Vic disowns him, Shane turns to the Armenian mob for help. Vic gets more involved with the San Marcos investigation, while Dutch and Billings are able to track down someone who survived the massacre.

Vic learns about his true status at the Barn from Hiatt. Shane gets involved with the daughter of an Armenian mob boss. Claudette begins to question Hiatt's loyalty.

As progress is being made in the San Marcos investigation, Vic receives bad news about his career. Meanwhile, Shane and Diro become business partners as she prepares to take over the Armenian mob.

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.

Claudette encounters a murderous old nemesis; Vic confronts Olivia about her political connections; Dutch's case gets personal.

Vic sets into motion plans to end the gang threat as his relationship with Cassidy deteriorates; Dutch and Billings investigate a possible sleepwalking murderer.

A prostitute from Vic's past is the key to taking down a violent drug dealer; Dutch worries about Claudette's health; Danny takes drastic measures to protect her child.

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

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.

Officers in the Barn investigate a woman's disappearance and the arrival of a large drug shipment; lives change forever.