Martin Riggs finally meets his match in the form of Lorna Cole, a beautiful but tough policewoman. Together with Roger Murtaugh, his partner, the three attempt to expose a crooked former policeman and his huge arms racket. The crooked cop (Jack Travis) thwarts them at every turn, mainly by killing anyone who is about to talk, but Murtaugh has personal problems of his own as his family are brought into the equation.

Riggs and Murtaugh are trying to take down some drug dealers but the they turn out to be not run of the mill drug dealers; they have automatic weapons and helicopters. Eventually they grab one of their vehicles and find a million dollars worth of gold coins or Krudderands in the trunk. Later Murtaugh is threatened by the men they're pursuing. That's when the Captain reassigns them to protect a man named Leo Getz who is suppose to testify in a big case. When they get to where Leo is, someone...

Martin Riggs is an L.A. cop with suicidal tendencies and Roger Murtaugh is the unlucky police officer with whom Riggs is assigned. Together they uncover a huge drug-smuggling operation, and as their success rate grows so does their friendship.

Martin Riggs and Roger Murtaugh, after escaping death from the previous movies are put on a hit list by The Triads. When blood thirsty mercenaries are on their tail they team up again with Leo Getz and Lorna Cole, a newcomer (Chris Rock) to finally put an end to the Triads for good.