When Jean Dupre's mother married an old man who's ranch was sitting on major radium deposits, they though they would be rich once he died. However, he left the ranch to his daughter, Marie. In order to scare Marie away from the ranch, Jean created a story about a giant king of the black bats who would one day descend from his cave and kill all the locals. He then dressed up in a black bat costume to make the legend come to life. However, their plan went awry when Sgt. Jim Reynolds of the mounted police came to investigate the sightings of the Black Bat.