The repercussions from the Money Train Heist continue to plague the Mackey family as Vic ignites a war between the Armenian mob and a powerful drug cartel with ties to the Mexican government.
Vic and Ronnie attempt to deal with the serious repercussions of Shane's involvement with the Armenians. A federal agent arrives to help investigate a recent wave of violence in Farmington. Meanwhile, a man who was acquitted of his wife's murder two years ago comes into the Barn to confess that he was responsible.
In light of the brewing Mexican-Armenian gang war, Pezuela orders a hit on Rezian, who tells Shane that his men have orders to kill both his and Vic's families if anything should happen to him. Meanwhile, the Strike Team looks into a series of murders believed to be the result of a "Top 10 Most Dangerous Gangs" list published by the Mayor's office. Billings' lackadaisical attitude gets under Dutch's skin during a murder investigation.
Vic works an angle to make himself valuable in the eyes of the Armenian mob, while Corinne finds herself in legal trouble. Meanwhile, Tina and Julien go undercover to catch a crooked adult film producer.
The gang war erupts in unexpected ways that Vic can't fully control. Dutch and Billings' homicide investigation grows into something more disturbing. Cassidy reaches out to Danny.
The Strike Team attempts to free a drug kingpin's kidnapped daughter. Claudette once again comes face to face with Kleavon Gardner whose trial is approaching. Meanwhile, Dutch continues to look into Lloyd being a potential serial killer.
Vic and Ronnie set up a meeting between the Mexicans and Armenians that they plan to manipulate, while keeping some important details from Shane. Meanwhile, Shane uncomfortably teams up with a former adversary to help the only survivor from a murder case that he worked on when he was in Vice. Dutch investigates a possible sleep-walking murder.
Vic faces additional pressure to take down Pezuela after his review board meeting is moved up. Meanwhile, a prostitute from Vic's past drags him and the Strike Team into a murder investigation. Dutch and Billings investigate a series of neighborhood break-ins, and Danny turns to the most unlikely person for help after Vic threatens to take her to court.
When his plan goes awry, Shane races against time to tie up any loose ends that will lead to trouble for him. Vic confronts a priest who might be harboring drug dealers. Dutch and Billings are close to finding two attempted cop killers, and Corrine learns some things about Vic.
The Barn is on the hunt for two fugitives. Aceveda encounters some obstacles to his quest to be mayor. Meanwhile, Dutch gets personal with a suspect's mother.
Dutch and Claudette acquire a new ally in the department's effort to take down Vic. Meanwhile, Vic tries to manipulate the situation with Pezuela, ICE, and Aceveda. Ronnie ponders whether he should give up fighting and leave.
Corrine agrees to work with Dutch and Claudette while also serving as go-between for Vic and Shane. Meanwhile, Claudette pairs Ronnie up with Julien to investigate the murder of a high school football player.
With time running out, Vic tries to secure an immunity deal for him and Ronnie in exchange for them helping ICE take down Beltran. Meanwhile, Dutch has to clean up Billings' mess and the Barn investigates a murder connected to a member of the Strike Team.
In the series finale, the Barn looks into a woman's disappearance and the arrival of a major drug shipment.