French nuclear tests irradiate an iguana into a giant monster that heads off to New York City. The American military must chase the monster across the city to stop it before it reproduces.

Sought by police and criminals, a small-time huckster makes a deal with a TV newsman for protection.

Against the backdrop of a noirish dreamscape, a tortured man returns to the city he swore he would never return to, in order to save the woman he has always loved yet can never have.