Dead bodies are being found in New York harbor. The police have no clues nor suspects until Nick and his colleague realize the killer is a giant octopus. Everybody, especially the police captain, refuses to believe Nick's story, and soon the harbor will be filled with boats for the 4th of July celebrations.
A dog is put in repeated and imminent danger in one scene, while his owner is dragged away screaming multiple times, but is eventually saved and reunited with their owner.