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.

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.