Bears and bullets at their backs, Lemslie, "Slim", and Bad stumble into a taxidermic nightmare wherein a spade doesn't strike true. But true enough to awaken a harpylike monstrosity that guts the man known as Doctor Vulchester, who, after his spilled innards slither back inside from a miraculous injection, offers them a deal: stop the mutants before they halt the train. That deed will yield 500 silver each plus freedom.