Hank Davis, a former stunt pilot, was the foreman of a massive power dam project, but attempted to sabotage the project as The Black Ace, because it would disrupt a mine that he was invested in. The Black Ace was the commander of the Mystery Squadron, a terrorist organization that flew fighter planes equipped with flame throwers. The Black Ace was a clever sort, an ace stunt pilot, and used a radio to broadcast his orders to the Mystery Squadron.