Riggs and Murtaugh's investigation of a drug cartel reunites Murtaugh with his former T.O. Riggs avoids the reality of Miranda's death by diverting himself with outside vices. Murtaugh and Trish struggle to find alone time.

Murtaugh delves deep into the psyche of a former navy seal who is wanted for criminal activity, and draws parallels between him and his partner, Riggs, who also served in the military. Riggs' connection to the suspect threatens to interfere with the case, but it also forces him to open up to Murtaugh.

Riggs and Murtaugh look into the murder of one of L.A.'s fashion expeditors and discover an underground DEA operation. With Trish and the kids away, Murtaugh goes on a 'bender'. Riggs has all-too-real dreams of Miranda.

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.

Murtaugh and Riggs suspect misuse of power in the LA Sheriff's department when they investigate the killing of a Texas Ranger.

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 and Murtaugh are forced to work with DEA agent Karen Palmer—again— to protect Leo Getz, an ambulance-chasing attorney who was linked to the Cartel. As the three delve further into the case, they begin to realize that Leo may not be the only one with a target on his back. Riggs begins to view Agent Palmer in a new light. Murtaugh is left worried after Trish makes a spontaneous decision.

Riggs and Murtaugh team up again with Palmer, and together they gain inside knowledge of dangerous new cartel operations. As Riggs’ attachment to Palmer deepens, so do his impulsive actions, further worrying Avery and Delgado. Trish explores the potential of an amazing new career opportunity.

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

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.

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.

Riggs and Murtaugh are led into the underground mob world as they investigate a murder in a hospital. Murtaugh learns that Riana is secretly dating his neighbor and nemesis' son. Riggs spends more time with his childhood friend. Scorsese's real name is revealed.

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 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.

Bailey's sister runs into trouble with the law, and she must decide how far she'll go to protect her family. Murtaugh must help Riana navigate boy problems. Riggs deals with the fallout of a night of heavy drinking.

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.

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.

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.