A massive and unprecedented tropical storm hits the Pacific, inflicting catastrophic damage upon the Polynesian island of French Polynesia. Not long after, a series of strange, unexplained events begin to unfold—a fishing trawler is destroyed near Panama, the wreckage of the vessel shows signs of a massive creature having caused the destruction. Dr. Niko Tatopoulos, a scientist specializing in the effects of radiation on animals, is summoned by the US government to investigate. Initial analysis leads to a shocking hypothesis: the creature is a mutated lizard, a result of nuclear testing in French Polynesia. This creature, which seems to be headed for New York City, is leaving a trail of devastation in its wake.

Upon arriving in New York, chaos ensues as the creature makes its presence known, evading the military's attempts to capture or kill it. As the city is thrown into a state of emergency, evacuations begin while the military strategizes on how to deal with the threat. Meanwhile, Tatopoulos discovers secrets about the creature's reproductive capabilities that exacerbate the danger it poses. Alongside a team of specialists, including a mysterious insurance agent with hidden expertise and a determined reporter looking for her big break, Tatopoulos races against time to unlock the mysteries surrounding the creature, as the city faces a battle for survival.