Jack and Buck head to the home of scientist Winston Redditch, whom they believe can help Jack with a special Jekyll and Hyde formula the scientist has "perfected"…

Battered and bruised after the Werewolf's battle with Atlas, Jack Russell returns to his apartment at Colden House to learn he's been evicted. Grabbing a few of his things, he takes a cab to the home of his friend Buck Cowan. Buck tells Jack he's been following the progress of a scientist named Winston Redditch, whose work has been inspired by the tale of Dr. Jekyll and Mr. Hyde, and could possibly provide a cure for Jack and his sister Lissa.

Jack and Buck leave for the scientist's home to meet with Redditch, who at that moment achieves a breakthrough. Deciding he is the only appropriate test subject, Redditch drinks what he thinks is the evil-subduing solution. However, he chose the wrong beaker, and he instead releases his evil side, naming himself DePrayve.

DePrayve meets his guests at the door, knocking them unconscious, then runs into town to wreak havok. Jack remains out cold until moonrise, when he transforms, and the Werewolf follows the maniac's trail to a grocery store where DePrayve menaces customers. They fight, and soon the police arrive, led by Lt. Victor Northrup, who is investigating the disappearance of his partner, Lou Hackett. The cops set up a net to trap the pair. DePrayve evades them, but they do successfully ensnare the Werewolf.