When members of the cable reality show SeaLife, aboard a ship in the South Pacific, respond to a distress beacon from Henders Island, several of the show's scientists wind up slaughtered by bizarre animals on the remote island. In response, the U.S. government blockades Henders Island to contain the serious biothreat it's unique fauna could pose to humanity. The ship's botanist, Nell Duckworth, joins the investigative team, which quickly finds that arthropods on the island have evolved into sophisticated and ferocious life forms. Particularly memorable and frightening are the creatures Nell dubs spigers, which have eight legs and are twice the size of a Bengal tiger.