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.