The Leader is a green-skinned scientific genius who was once an ordinary laborer at a chemical research plant. An accident exposed him to gamma radiation and transformed him into an extraordinary intellect. Believing that his intelligence makes him capable of ruling the world, he develops an army of apparently indestructible Humanoids and plans to seize control of the world's nuclear weapons. His first target is a military shipment containing a nuclear device overseen by Dr. Bruce Banner.
The Leader controls his Humanoids through a cybernetic headpiece and monitors their surroundings through a spectroscopic transceiver. When his first Humanoid fails to secure the nuclear device, he sends a horde of machines to Astra Island to capture Banner's Absorbitron and bring the Hulk to him alive. The Hulk repeatedly frustrates his plans, and the Leader becomes increasingly determined to discover the source of the creature's strength. He ultimately suspects that Banner himself is the key and contacts a colonel whose forces have captured the scientist.