After being horribly mistreated at a government animal research facility, Snitter and Rowf escape into the isolation, and terror, of the wilderness. Aided only by a fox they call ''the Tod,'' the two dogs must struggle to survive in their new environment. When the starving dogs attack some sheep, they are labeled ferocious man-eating monsters, setting off a great dog hunt that is later intensified by the fear that the dogs could be carriers of the bubonic plague.