When an epidemic of cockroaches spreading disease infests New York City, Susan Tyler (Mira Sorvino) and her husband Peter Mann (Jeremy Northam) are called on to create a superbug to kill them off. The Judas Bug as they call their creation is designed so that it will supposedly die off after several months without the ability to reproduce, unfortunately they underestimated their own creation which quickly becomes a deadly force of its own, living and breeding in the subway system. The Judas bug adapts quickly and begins to imitate other creatures, including humans, and Susan and Peter must go underground with Leonard (Charles S. Dutton), a transit employee, as their guide they must attempt to stop them before it is too late.