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.

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.

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.

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.

When Cole is investigated by the FBI, Murtaugh is forced to question his loyalty to his own partner. Meanwhile, Cole works a case that puts Natalie's fiancé, Andrew, into the crosshairs right before their wedding day.

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.

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.

When Riggs and Murtaugh attend Leo Getz's surprise wedding, they end up investigating a missing person. Riggs comes face to face with someone from his past. Murtaugh receives news that might change his life forever.

After a mansion break-in turns into a homicide, Murtaugh and Riggs set out to find the culprit. Murtaugh and Trish question their trust in Riana as she gets into some trouble with new friends. Riggs recalls his troubling childhood and finds a true family with Molly and Ben.

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 confronts his past when his former mentor delivers alarming news, as he and Murtaugh investigate a robbery of safe deposit boxes. Murtaugh clashes with Trish's new client and enlists Bailey's help to investigate her.

Murtaugh turns to Cole's former mentor for help on a high-stakes cartel case. Murtaugh and Trish meet Natalie and Maya for the first time. Tensions mount between Bailey and 'The Gute' as the new partners begin to work together.

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.

After the fatal end to an argument on a construction site, the squad works to untangle facts about the incident. Riggs struggles to rekindle his relationship with Molly. Trish's job is on the line as she tries to close a big deal at work. Murtaugh gets one last chance to make it right at home.

On Murtaugh's first day on the job as interim captain, the wife of a popular businessman is abducted and the squad finds a connection in the case to Rigg's father. Riggs is left to grapple with his family and work.

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.

Riggs takes a trip down memory lane while visiting his father-in-law in prison, which reminds him about an old secret regarding his deceased wife.

The duo sets out to unlock a case about a veteran hitman who Murtaugh has followed for years. Riggs struggles to find a connection with his father. Murtaugh scares Riana with his overprotective driving lessons. The team members finds themselves wedged in a dangerous incident that tests their trust.

Murtaugh and Cole investigate a robbery of a truck filled with fine art. Cole deals with lingering feelings for Natalie following a new development in her life. Riana blackmails Murtaugh into letting her go to a concert after she catches him in a lie that he told Trish.

Cole finds himself on the rebound after Natalie's engagement, and his new romantic interest, Julie, has an unexpected connection to A.D.A. Erica, complicating things at work. Meanwhile, Murtaugh worries about the connection between the murder he's investigating and a new opportunity for Trish to serve as co-counsel on a high-profile lawsuit with Leo Getz.

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.

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 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.

Murtaugh and Riggs respond to a robbery that takes place 20,000 feet in the air. The investigation turns into an ongoing hunt for an unreliable father, with his daughter being their main witness. Murtaugh faces hostility from his daughter as he tries to connect with her.

Murtaugh and Riggs investigate a death that occurs moments before the victim's bet wins a horse race. Leo Getz insists it's a homicide and aids in the investigation. Murtaugh updates his will. Riggs struggles to come to terms with his past.