Politically ambitious new LAPD captain David Aceveda tries to crack corruption in the Barn by recruiting Terry Crowley to help him take down fellow detective Vic Mackey, leader of a police Strike Team consisting of himself, Shane Vendrell, Curtis "Lem" Lemansky, and Ronnie Gardocki. Meanwhile, detectives Dutch Wagenbach and Claudette Wyms investigate a woman's murder only to discover her missing daughter has been sold off by her addict father to a child molester.

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.

Aceveda insists that Vic take uniformed cops in with them to bust an Armenian gang's drug delivery. After the bust, Julien sees the Strike Team take a portion of the drugs for themselves.

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.

Tension within the group begins to mount as the Strike Team attempt to rectify a mistake Vic made when he decided to use some of the cash from the stolen money train during a botched gun-running sting. Meanwhile, Dutch and Claudette seek the help of a college honor student named Esteban who was the only survivor in the murder of two latin gang members, one of them being his close friend.

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.

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