Murtaugh and Riggs investigate the mysterious death of famous singer Shaye's bodyguard. Murtaugh turns to his daughter—a fan of the singer—to learn more about Shaye's background and uncover the possible suspects. Riggs learns the responsibilities that come with being in a relationship with help from Murtaugh.

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.

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 investigate the death of a surfer. Murtaugh grows suspicious of Trish's new friend, with whom she's been working on a charity event—and then learns it's NBA champion Scottie Pippen. Riggs has violent nightmares that bring up scars from his childhood.

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.

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.

Murtaugh and Riggs search for the culprit of a local jewelry heist. Murtaugh gets called 'grandpa' by another parent while at the playground with Harper, sending him into a tizzy. Riggs deals with withdrawal from drinking.

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 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.