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.

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 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.

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.

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.

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.

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.