Claire Gregory, an upper class New York personality, witnesses a murder in a luxurious nightclub. Detective Mike Keegan, recently promoted, is assigned to protect her.

Veteran buttoned-down LAPD detective Roger Murtaugh is partnered with unhinged cop Martin Riggs, who -- distraught after his wife's death -- has a death wish and takes unnecessary risks with criminals at every turn. The odd couple embark on their first homicide investigation as partners, involving a young woman known to Murtaugh with ties to a drug and prostitution ring.