Inhabitants of a planet where all people derive super-powers from any variety of sunlight but are powerless in darkness. Superman, pursuing the Four Galactic Thiefmasters, is tricked into being trapped on the Thorone homeworld.
Using his wits and intelligence on the dark side of the planet where no one has super-powers, Superman constructs a variety of robots and uses psychological bluffs that impress the planetary inhabitants, allows him to escape, and dissuades the Thorones from invading Earth.
Lahla (with the prophetic two "L"s in her name), a native woman, is smitten with the powerless Superman but upon learning of his prowess as the mightiest man in the universe, later prefers a meek resident of Earth in his place (Act No. 321/1, Feb 1965: "Superman--Weakest Man in the World").