A mutant sheep is on the move near a ranch in the American West.

A Large mutated sheep Embryo is discovered by a rancher .The mutant is whisked away to the secret lab of Dr. Clemens and his faithful assistant Mariposa. Dr. Clemens discovers that the old mine gives off some strange Phosphorus vapors that may be the cause of the mutation, as well as being the origin for the old legend of a monster that once haunted the area. Clemens puts the Creature in an Incubation Chamber and it's not long before the mutant sheep has morphed into an 8-foot monstrosity, which escapes & terrifies the town.