A war is waged in Heaven by one of the Angels named Lucifer. He decided to rebel against God and separate himself from the rest of the Angels by leaving Heaven and roaming the earth.

Millionaire Mason Murphy renovates the haunted Mayhew mansion. He plans a tremendous lunar eclipse viewing party to celebrate his return to his hometown of River Ridge Iowa. At the party, magic runs out of control and the party guests are murdered one by one.

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.