It turns out that monsters are lurking beneath the streets; beings that were once human, but have been mutated by radioactive, chemical toxic waste into hideous, flesh-eating creatures that prey on the homeless who live in the underground. Given the recent drop in the underground transient population, the creatures have resorted to coming to the surface through sewer manholes to feed. Through a series of events, both George and A.J. find themselves trapped in the sewers, a reporter gets involved and eaten, and Lauren has a problem with both a clogged shower drain and a mutant that comes up through the sewer access point that she opened in the basement of her apartment building.