As a result of tampering with biogenetic code by an American company in Japan, the mutant creature Nezulla, classified as Hybrid (biology), and half rat, escapes its containment and goes after the ill-fated scientists that spawned it. To cover up the atrocity, the authorities condemn the lab. Eventually when a bacterium found in the lab enters the sewer system, a squadron of soldiers is deployed to clean up the mess. Upon entering the lab via the sewers, the troops are slaughtered one at a time by Nezulla, whose armor like skin easily deflect their bullets.