Miller, a university professor, and two of his students take a trip out to a spoil island in the middle of Santa Rosa Sound in the Florida Keys to study the effects of pollution on the flora and fauna. While they are there, a tide of black microbes is released into the river, and floods down and around them. They escape by burying themselves in the sand, but when they emerge, it is to a world which is strangely silent and changed. Before long, burning figures are glimpsed along the distant banks, dragging themselves into the water. Then the attacks start. With daylight their only weapon, Miller realises that time is running out as an army of the living dead, intent on feasting on their flesh, is gathering in the surrounding waters.