In the near future, an atomic disaster has reduced the world to poverty. Instead of a government, America is run by an organization called the Merchants, who exploit the degenerate remains of society. In order to keep control of the populace, the Merchants force Dr. Paul Dean to create a new life form, a parasite that feeds on its host. Realizing the deadly potential of such a being, Dean escapes the Merchants with the parasite, infecting himself in the process.