Welcome to Endtown, a community of animal-like mutants and "impure" humans infected with a mutagenic virus living below Earth's post-apocalyptic surface. Driven by hunger, they venture out only in search of food, but must face bloodthirsty, mutated monstrosities and the constant threat of the Topsiders; un-mutated, technologically advanced humans bent on exterminating all mutations in order to create a genetically purified humanity.

After a barfight and mugging leave outsider Wally Wallechinksy in the hospital with a head injury, Holly Hollister takes on the responsibility of caregiver, despite Wally's hesitation. When his good health returns, Holly and Wally set off to find the man who stole Wally's belongings, but end up finding a bit more than they bargained for.