Season four focuses on themes of courage, both in the personal and professional lives of the squad. Plus, Rusty, who is now officially adopted by Sharon, finds a passion that drives him — something Provenza is not too pleased about.
The squad investigates a double homicide related to an ongoing string of home invasions in the Hollywood Hills. Meanwhile, Sanchez attempts to reintegrate himself in the division after his suspension over a questionable use of force, while Captain Raydor makes a fateful choice in the life of her adopted son, Rusty.
When a dead body pops out of the trunk at the end of a car chase, the squad must untangle connections between a superstar chef; a middle-aged pediatric psychiatrist and his second, much younger wife; and a bankruptcy lawyer whose problematic representation threatens to derail the investigation. Rusty continues his attempt to identify the murder victim who called herself Alice Herrera, inadvertently threatening the case against her murderer.
Major Crimes investigates the murder of a super model with close ties to a pompous celebrity photographer (Jamie Bamber) with boundary issues. Meanwhile, Raydor and Rusty give Assistant Chief Taylor a headache when they are both served subpoenas for their entanglement in the Alice murder case.
During his first drive-along as a reserve officer, Buzz Watson discovers a dead body in a hotel room bathtub, not only threatening an extremely expensive wedding but also Flynn and Provenza's plans to take the division to a Fourth of July Dodgers game.
While the Major Crimes unit investigates a complicated gangland shooting, Det. Amy Sykes finds she must protect the identify of a witness capable of identifying the killer. Rusty struggles with how to manage newly gained information on the Alice case, and Lt. Flynn works to gain the courage to take his relationship with Captain Raydor to the next level.
When the squad comes across a pile of bones, they fall into a web of connections as they find their victim has an unnerving past. Rusty continues to pursue his investigation of the Alice case with the help of a new friend. Meanwhile, Rusty also gets roped into helping Provenza make a major move.
After a shooting leaves two LA police officers dead, the Major Crimes unit must work with the Deputy Chief of the LAPD Special Operations Bureau, Fritz Howard, to piece together a high stakes case involving a fugitive witness. Meanwhile, Rusty works with the team on the case in order to secretly gather more background information to support his own, journalistic investigation into the life of the girl who called herself Alice Herrera..
New information prompts the re-opening of an old kidnapping investigation, forcing Captain Raydor and her Major Crimes Division into partnership with a potentially corrupt FBI agent. Rusty has a major breakthrough in his investigation on Alice Herrera, but discovers he and T.J. are possibly not the friends he thought they were.
The division investigates an online video of a bloodied, half-naked man walking down a street with a gun. Meanwhile, Rusty at last finds Alice Herrera's brother and reaches out to Sharon for help.
After Major Crimes identifies a murder victim as the son of State Superior Court Judge known for being tough on criminals, the squad hunts through her current case load, which involves an Aryan motorcycle gang and, much to their surprise, connected to the disappearance of a thirteen-year-old boy.
Four wealthy one percenters are left for dead outside a hospital emergency room in a twisty- curvy murder that leads through an impossible list of suspects, including a high school daughter with her father's iPhone password, a diabetic chauffeur, the owner of several LA parking lots and a mysterious woman with great legs who trips up Lt. Andy Flynn on her way to Mexico. Meanwhile, Rusty pursues a taboo subject for his next story on "Identity."
Jack Raydor (guest star Tom Berenger) is back again, defending a man who is attempting to withdraw a confession in the murder of his wife. A last-second video purporting to provide the defendant with an alibi alerts the Major Crimes team to the possibility of a conspiracy. Rusty interviews Slider, while Flynn is still living with Sharon due to his injury.
Sharon and the team investigate a murder during the taping of a reality competition show pitting married couples against each other. The case has a profound effect on Sanchez, bringing back memories of his late wife. Meanwhile, Rusty meets Slider's lawyer.
The Major Crimes team is called to investigate a follow up attack on a victim of road rage, as a business executive and his wife fall prey to a furious driver in a pickup truck. As Thanksgiving approaches, Flynn suffers a setback on his road to recovery. And Rusty finally gets the interview with Slider that he wanted.
Sharon and the team investigate the murder of a young man pushed off the top of a parking structure who was somehow able to afford a high-end apartment without any visible means of support. Meanwhile, Lt. Andy Flynn suffers through the ministrations of an overly cheerful physical therapist.
With Flynn on desk duty as he recovers from injuries, Sharon and the team investigate the murder of a fugitive diamond thief whose body was found by his bail bondsmen. Rusty is put in a tight spot when his relationship with Slider is discovered by Marianna's brother.
A professional baseball pitcher's daughter goes missing, and the Major Crimes team's investigation leads them to the very limits of the justice system. Rusty is put in an extremely awkward position as Slider approaches the last phase of his trial.
Sharon and the team track an unhinged killer making his own film with his victims as the stars as a new romance takes wing.
A young woman and her 3-year-old son are shot to death while driving through gang territory in the wrong colored car, and the gun used in the murder is quickly connected to the most troubling series of unsolved homicides in LAPD history. As Captain Sharon Raydor and the rest of her division attempt to solve the mystery, Amy Sykes begins an uneasy alliance with a disgraced former LAPD detective with a novel theory and a corrupt past.
A startling discovery is made in a church. Meanwhile, Stephanie and Sanchez bond over lost loved ones; Rusty discovers that his biological mother's ex is an on-the-run fugitive; and Tao is pushed too far by an old partner.
When another victim is found, Sharon angrily turns her attention back to former LAPD Det. Mark Hickman; Fritz and his team help the LAPD show up in force at Tamika's funeral; Tao makes a discovery involving Peter Goldman.
Information pours in about past victims; Lt. Cooper and Amy Sykes are caught in an unexpected gun fight; Sharon makes her way toward the truth.
The threads of seven murders are tied together; the field of suspects is narrowed to three; Mark Hickman confronts the truth about his past; Sharon uses an unreliable witness; Provenza and Patrice solve their wedding issues.