Thomas Craven is a detective who has spent years working the streets of Boston. When his own daughter is killed outside his own home, Craven soon realizes that her death is only one piece of an intriguing puzzle filled with corruption and conspiracy, and it falls to him to discover who is behind the crime.

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.