Challengers of the Unknown#8(1959)

The Challengers are visited by their honorary member June and her friend Marie, who has inherited an ancient castle in Mordania, in which she has found, in a secret compartment, a scroll. The Challengers are intrigued by the scroll, and when they decode it, they decide to check the castle out. In the catacombs beneath the old heap, they find a box, open it, and get sprayed with an alchemical youth serum. Ace and Rocky are rejuvenated back to about junior-high-school age. While the team is distracted, Drabny enters the room, steals the box, and escapes through a hidden door. When the Challengers pursue him on foot, Drabny uses his Elemental Helmet to open the ground under their feet. He gets away. Drabny rejuvenates himself and takes over Mordania, residing now in the royal palace, another ancient castle set within the capital city. Prof and Red infiltrate this base but get captured. Mary, June, Ace, and Rocky then rescue them from Drabny's prison. They recover the age reducing spray, seemingly left behind in great haste by Drabny, and escape from the palace into the capital city. Drabny has left town, with some troops, to confront some government troops, out in the hills. Conventional tanks approach Drabny's position, where he has at least five "Star Cars", armed with futuristic weapons. The Challengers arrive before the Mordanian Tank Corps, and amid some very kinetic fighting, in which some heavy tanks are lofted skyward, Ace Morgan manages to get aboard Drabny's personal vehicle, and douse him with Youth Serum. Morgan dons the Elemental Helmet and gets the levitated government tanks safely back on the ground, then captures Drabny, alive. The Challs give him a brisk spanking before turning him over to the authorities. Afterward, Ace Morgan tells Marie and June that Drabny is imprisoned, the Youth Serum supply is exhausted, and the helmet and goggles have been destroyed.