We open two weeks after Murtaugh went after Riggs. We're in Mexico.
Tito Flores is still alive, but Murtaugh hasn't found Riggs. He's on the phone with Trish and she's not happy.
Murtaugh finds Riggs at the hotel. Riggs has Tito hostage in a hotel room. Riggs is about to shoot Tito when Murtaugh barges in and tries to convince Riggs not to kill Tito.
One of Tito's men shows up and a shootout ensues. Riggs and Murtaugh take Tito out and throw him in the truck.
Back in L.A., Avery is being investigated about the incident in Mexico.
Murtaugh is in the hospital getting his finger reattached that he lost when Riggs smashed the trunk down on his hand.
Avery and Riggs go to show Tito in the trunk but find that Tito has been shot in the head. Riggs and Murtaugh are being questioned by the investigation committee. Riggs and Murtaugh are both suspended.
Riggs isn't interested in finding who killed Tito.
Murtaugh arrives home to find Riana and RJ having a party. Rog is not happy about anything and he and Trish fight. Riggs returns to his trailer where he starts drinking.
Dr. Cahill makes a visit to check on him.
Roger shows up at the urgent care facility where he lost his finger. The nurse locks him out, but then Tito's men show up to kill the nurse. Roger throws her in a closet and prepares to fight the gang with a scalpel! Riggs shows up just in time to take the guys out before they kill Murtaugh.
Murtaugh questions the nurse about who she told about Tito. Murtaugh calls Bailey to get information. A guy comes in and admits to Tito's murder.
Riggs goes into the interrogation room to ask the perp what is was like to kill Tito Flores. He doesn't get a satisfactory answer and leaves.
Murtaugh got dinner for everyone to make up for his horrible behavior. They are having a family discussion when Riggs shows up. He tells Murtaugh that he doesn't think the perp didn't kill Tito.
Avery tries to get Riggs and Murtaugh reinstated. Bailey interrupts with information that Barnes didn't do it. Riggs and Murtaugh question Barnes again about the murder.
Barnes admits to not killing Tito. He tells his story and that Raul (Tito's second in command) was the one who killed Flores.
Riggs is going back to Mexico to take down Raul and the end the cartel once and for all. Murtaugh wants to do it the right way.
In Mexico, a funeral is being held for Tito. Riggs barges in. The men pull their guns, but Riggs is armed with grenades. In a back room, Murtaugh is getting other things ready.
Riggs tells Tito's men Raul killed Tito, but Raul denies it. Murtaugh is supposed to be playing the tape for everyone to hear. Eventually, the tape plays and the men point their guns at Raul. A shootout ensues and Raul agrees to tell Riggs everything if he saves his life.
Murtaugh and Riggs head back to LA with Raul. They are reinstated. Dr. Cahill meets Riggs in the elevator and sees that he's returning to the force.
Riggs visits Miranda's grave and buries his ring.
The Murtaughs are having another party and Riggs shows up with tequila.