While on a trip to the Amazon, photographer Gregory Haig comes across a strange animal a group of illegal loggers removed from the jungle. He is injured while trying to photograph it, but then travels back to the U.S. with his anthropologist girlfriend, anthropologist Diane Stewart. They go to his family's private island for a family reunion, but while a tropical storm bears down on them, he gets ill and then transforms into a vicious creature with the ability to turn other people into its species. The inhabitants of the island struggle to stay alive throughout the night as they fall victim to the nightmare monstrosity's hunger and urge to reproduce.
