One hundred miles off the coast of Puerto Rico a top secret experiment too dangerous to be conducted on land is being conducted aboard the U.S. nuclear attack submarine Sam Houston&mdash;an experiment that has gone horribly wrong.<br/><br/>A predator is loose in the Sam Houston&mdash;a microscopic killer that strikes without warning driving its victims to terrifying heights of violent self-destructive insanity.<br/><br/>Soon madness and terror reign eight hundred feet below the ocean&#39;s surface as those infected race to defeat the silent killer&mdash;unaware that another enemy follows in their wake. A diesel submarine relic is pursuing nuclear-powered Sam Houston into a final deadly confrontation in the deepest waters of the Atlantic.