A slightly unhinged former Navy SEAL lands a job as a police officer in Los Angeles where he's partnered with a veteran detective trying to keep maintain a low stress level in his life.

A noise complaint at a boxer's home leads Riggs and Murtaugh to a case involving illegal gun runners and Riggs becomes personally invested in the outcome when one of their targets reminds him of his late wife. Trish worries about Murtaugh's health.

A string of burglaries hits close to home for Murtaugh when one occurs in his own neighborhood, and it gets just as personal for Riggs when another break-in ends in a casualty. Roger Junior connects with an old friend who might be twisted up in some criminal action of his own.

The investigation of a young model's murder leads Riggs and Murtaugh to one of L.A.'s wealthiest families and Riggs is jolted when an old friend of his wife's is also linked to the case. Murtaugh is shocked to discover that his daughter is sending racy photos to her new boyfriend.

When a million dollar casino heist takes a deadly turn, Riggs befriends the only credible witness, an eight-year-old boy, and takes him into his care. Murtaugh pulls some dangerous stunts in an attempt to prove to everyone that he can be a motorcycle guy. Riggs contemplates what to do with the money he received from selling his home in Texas.

The whole precinct’s holiday celebrations are cut short when they’re called to examine a ruthless homicide.

After investigating the murder of a millennial 'designer drug' dealer, Riggs and Murtaugh find themselves in a violent turf war between a new generation of drug dealers and a Koreatown gang. Murtaugh finds some comfort in a temporary new partner. Trish attempts to set up Riggs with her co-worker.

When a car containing massive amounts of cocaine is stolen from an impound lot, Riggs and Murtaugh become embroiled in a notorious car theft ring. Murtaugh experiences some frightening chest pains. If Riggs' driving isn't enough of a trigger, the lead defense attorney on the case is none other than the terrifyingly brilliant Trish Murtaugh.

Riggs and Murtaugh examine a series of violent crimes with one thing in common—the victims are all members of the same church. Riggs faces a moral dilemma when the one-year anniversary of Miranda's death sends him to a new low. Trish and Roger disagree with RJ about his future.

Riggs makes a shocking discovery about Miranda’s death that leads him back to the cartel in a frantic search for answers. His wild desperation leaves Murtaugh torn between his commitment to his partner and his commitment to his family.

Murtaugh follows Riggs down to Mexico, where he plans to avenge his wife's death and finish off Tito Flores once and for all. Once back in the States, they have a few people to answer to during the ongoing investigation around Flores, including Murtaugh's family. Avery is questioned by Internal Affairs about the integrity of his department.

A doctor is found dead in the pool of a wellness clinic. Riggs suspects a drug angle and asks Agent Palmer for help.

Riggs is reunited with childhood friends and comes to realize they might be mixed up in the robbery-homicide case he and Murtaugh are investigating. Murtaugh finds a joint stashed in his kitchen that he brings to Scorsese for testing in effort to bust one of his kids.

It's Christmas time and the Murtaugh family is headed to Hawaii. Murtaugh's vacation is put on hold when he and Riggs are called to a homicide and the victim is an old friend. Riggs gets a surprise phone call from a relative just in time for Christmas.

Riggs and Murtaugh are thrown into the world of counterfeit money. When a group of teenagers inadvertently gets involved, it strikes a chord with Murtaugh, who is dealing with his own issues regarding his son. Riggs decides to pay a visit to someone from his past.

Murtaugh and Riggs respond to the murder of an escaped patient of Dr. Cahill's who mysteriously goes off the rails. Riggs' anger gets the better of him once again, causing Avery to consider whether or not he is fit to serve. Family tension runs high between Murtaugh and Trish, who have to make big decisions about R.J.

After the city's gun buy-back program is robbed, the team is on a hunt for those responsible. Murtaugh walks on thin ice with Trish. Riggs finds an unlikely friend in Ruthie. Avery is reunited with a college 'frenemy' who has key information about the case.

The squad is on high alert after an apparent threat is made on Riggs' life. With Murtaugh taking on more responsibility at work, he and Riggs have to deal with their changing relationship. Trish gets caught up in some trouble. Molly asks Riggs to make a big decision about their future.

Former international CIA operative, Wesley Cole returns home and assumes duty as a police officer with the LAPD. Cole will find himself navigating a new partnership with Murtaugh, as he adjusts to life in Los Angeles. Avery continues his campaign for city council.

New partners Murtaugh and Cole attempt to find a steady rhythm as they work to solve the murder of a finance executive. Cole navigates his role with his ex- and his daughter. Avery grapples with the outcome of his campaign for city council.

Cole juggles the realities of his job and his duty to be a good parent, as he and Murtaugh work together to bust a gang running a lottery scam. Murtaugh gets ready to celebrate his 30th anniversary with the LAPD and receives a surprise visit from his competitive father-in-law.

Cole reflects upon his time working for the CIA, as a person from the past makes a startling reappearance. Murtaugh struggles with his own mistakes, after a murder raises questions about a suspect he put away years prior. Leo Getz returns as the attorney on the case and tries to convince Trish to join his team.

While Cole gets into the holiday spirit for his first Christmas with Maya, Murtaugh hopes he can convince RJ to come back home from Costa Rica for the holidays. Cole and Murtaugh are saddled with a complicated burglary and home invasion case. Avery's holidays are a bit blue. Bailey is still trying to figure out her new partner.

Murtaugh takes a family vacation, but is pulled back into work when he witnesses an alleged abduction. Cole is left to investigate a murder himself, but the two cases begin to intersect. Meanwhile, Erica's mother, Senator Malick, comes to town and stirs things up between Erica, Cole and the case at hand.

When Cole and Murtaugh investigate a case involving a father and daughter crossing the Mexican border, they end up uncovering a major issue with California Boarder Patrol. Meanwhile, Trish prepares her campaign for D.A. and must face parts of her past, before they find their way into the media spotlight. Cole also confronts his past when he experiences flashbacks as a result of an injury.

Against Murtaugh's advice, Cole reaches out to Tom Barnes to help with a case that hits close to home, putting Murtaugh and Cole's partnership to the test. Meanwhile, Trish prepares to announce her campaign for District Attorney.