A bizarre series of murders in New York City seems to point toward the existence of a race of mutant cannibals living under the streets – they are the Cannibalistic Humanoid Underground Dwellers!
The opening of the film presents us with a woman (Laure Mattos) walking her dog down an empty, darkened city street. As she passes by a manhole, she is attacked by a creature, and the dog is pulled in after her.
George Cooper (John Heard) lives with his girlfriend Lauren (Kim Greist). George, a once-prominent fashion photographer, has since forgone the fame and fortune. His current project is photographing New York City’s homeless population, specifically those known as “undergrounders”, or people who reside within the bowels of the city.
A police captain named Bosch (Christopher Curry) is introduced. Bosch has a personal interest in the recent flood of missing persons (most of whom are homeless) being reported to his precinct. Bosch interviews A.J. “The Reverend” Shepherd (Daniel Stern), who runs the local homeless shelter. Shepherd believes recent events to be a part of a massive government cover-up and has the evidence to prove it. Bosch’s superiors know more than they are letting on and seem to be taking their cues from an overly glib, weasely type named Wilson (George Martin), who works for the Nuclear Regulatory Commission.
It turns out there are monsters 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 but now due to a shortage of homeless people they have taken to the surface to feed!