Dr. Darkk was a scientist with a broad range of interests including optics and robotics. His research, however, was costly and to underwrite these efforts, the scientist became a criminal. His first recorded crime was in 1941 when, with assistants Nan and Butch, he staged a heist at a New York jewelry store. Using a light ray hidden in a ring invented by Darkk, Butch turned the jewels invisible and made off with the store's best diamonds. Darkk acquired loot was used to finance his research, often by purchasing supplies from Bannermain Chemical. The size and exotic nature of the purchases aroused the suspicions of Rex Tyler.
Resolving to investigate the case himself Tyler delivered Darkk's next order. However, his naiveté of Darkk's delivery procedures forewarned the thugs of his plans and he was left unconscious in the cellar of Darkk's rural laboratories. Upon regaining consciousness, Tyler quickly switched to his identity as Hourman and followed Nan to an abandoned light house which served as Darkk's true hideout. After a confrontation with Darkk's guard dogs and dispatching Butch, Hourman confronted Darkk. The criminal scientist was prepared however and unleashed a giant robot of his own design named Giganto. When Hourman bested his robot, Darkk used his ring to make himself invisible. Undetectable to the hero, Darkk knocked Hourman out and fled. Along with Nan, Darkk abandoned Butch and fled to intercept a plane carrying a large fortune in war bonds. Furious at their betrayal, Butch helped Hourman track the two criminals and after a quick defeat, Darkk and his assistants were turned over to the authorities.