A young woman wanders around New York City and stumbles across a number of strange characters and settings that represent the "underground" areas of the city. She sees stand up comedy in Central Park, a prostitution auction, a voodoo ceremony, an S&M club, and a number of very interesting performance artists. These are just a few of the sights and sounds of New York that she encounters.
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.
Test pilot Tuck Pendleton volunteers to test a special vessel for a miniaturization experiment. Accidentally injected into a neurotic hypochondriac, Jack Putter, Tuck must convince Jack to find his ex-girlfriend, Lydia Maxwell, to help him extract Tuck and his ship and re-enlarge them before his oxygen runs out.