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 maintain a low stress level in his life.

Murtaugh and Riggs target a former Navy SEAL. Murtaugh sees a parallel between the suspect and Riggs. Murtaugh sees Riggs connection to the suspect threatens to interfere with the case.

Holiday celebrations are cut short when the precinct is called to examine a homicide linked to the deranged nephew of the drug lord who has ties to Riggs; and Murtaugh has a problem with his neighbor's excessive holiday decorations.

Riggs and Murtaugh end up in the middle of a turf war as they investigate the murder of a millennial "designer drug" dealer.

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

Roger and Trish find themselves pitted against each other when a stolen car full of cocaine is traced to a ring of car thieves.

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.