The film opens with a disease threatening to wipe out a generation of children. Dr. Susan Tyler, played by Mira Sorvino, is an entomologist who recombines the DNA of insects to create a species that will destroy the cockroaches that carry the disease. She calls the species the Judas breed and they succeed in eradicating the epidemic. But three years later, Tyler discovers that the Judas breed has evolved into a lethal predator. Plagued by guilt, she seeks advice from her old professor Dr. Gates, played by f. Murray Abraham.