Los Angeles police sergeant Roger Murtaugh, who has just turned 50 years old, is assigned to investigate the death of Amanda Hunsaker, a prostitute who is one of the daughters of bank president Michael Hunsaker, a friend whom Roger has known since they were in the Vietnam War together, but Roger hasnt seen Michael in 12 years. Beginning with this investigation, Roger is assigned a new partner Sergeant Martin Riggs, who has been suicidal ever since his wife Victoria Vicky Lynn Riggs died in a car crash in 1984. Riggs and Murtaughs investigation of Amandas death reveals that she was murdered. Upon hearing of this, Michael tells Murtaugh that he would like for whoever is behind Amandas murder to end up dead, like Amanda. Riggs and Murtaughs investigation continues and it makes them the targets of Shadow Company, a group of former Vietnam War era mercenaries who now bring heroin into the Los Angeles County region. Shadow Companys leader, General Peter McAllister, and his right hand man, Mr. Joshua, want Riggs and Murtaugh dead, no matter what the cost.