While on an experimental rocket, Clark and Lois encounter the alien Brainiac, who plans to shrink and bottle the great cities of Earth and then use them to repopulate his planet. Superman gets inside Brainiac’s ship when the villain snatches Metropolis and there finds a bottle with the Kryptonian city of Kandor. He enters the bottle and with the help of a scientist there restores the cities of Earth while Brainiac lies in suspended animation for his trip home. Because there is not enough power to restore Kandor, Superman places the city in his Fortress, as Brainiac rockets away empty-handed.; Criminal John Corben, who is nearly killed in an auto accident, is given a robot body powered by uranium. When he is hit by bullets meant for Lois, she assumes he is really Superman. Recognizing a good idea, Corben impersonates Superman to collect more uranium. Running out of sources of uranium, Corben learns that he can also be powered by kryptonite. But he doesn't realize that the kryptonite he steals is fake, prop kryptonite and collapses.; Superman recalls his college romance with Lori Lemaris, a mermaid from sunken Atlantis.; Jimmy Olsen is given the gift of a magic totem bestowing 3 wishes on the owner, he uses one wish to give Superman a super companion - Super-Girl.