On a parallel Earth-166, Superman is married to an unnamed woman, and has non-identical twins that he names Jor-El II and Kal-El II. Only Jor-El II develops super-powers, as Kal-El II takes after his mother, and Jor teases him repeatedly about it, until Superman points out that teasing and bullying are wrong. But it's too late. Kal wants very little to do with Jor and has developed an inferiority complex.
Superman discovers a distant planet where the rare twin-suns rays give Kal-El II powers while he's there, but he soon becomes homesick and asks to return to Earth. And while young Jor-El II accompanies Superman on missions, a Robot must protect Kal and his mother from racketeers.
To put the twins on equal footing, they are sent to Kandor University. Despite their lack of powers, Jor-El the second continues to excel physically, while Kal-El the second sticks to books in the Kandor museum - especially stories of the Phantom Zone.
But when the Mystery Raider breaks into the museum to steal the rare element Volium, the El twins find the Nightcave and - like Superman and Jimmy Olsen - put on the costumes of Nightwing and Flamebird.
As Jor-El II prefers action to thought, and Kal-El II's historical contributions are ignored, the Mystery Raider steals enough components to build his De-Evolutionary Ray, which creates atavistic monsters. The Raider escapes pursuit, and leaves Kandor to wreak havoc on Earth.
Jor-El II leaves with Superman to hunt the Raider - while Kal Junior takes the Legion's Time Bubble back to pre-cataclysm Krypton and is apprenticed to his grandfather, Jor-El the first. He calls himself Kalel Kent. They travel to see the work of Gann Artar who has built a De-Evolutionary Ray. The Kryptonian Science Council forbids such research, and Gann swears revenge.
Jor-El has noticed a remarkable family resemblance in Kal-El II — even though his own son Kal-El isn't born yet — and takes him to the El Family Vault to compare Kal Junior to his ancestors.
Gann follows Jor-El and creates monsters on Krypton that Jor-El I restores with an antidote. Defeated, Gann Artar is sentenced to 50 cycles in the Phantom Zone. Kal-El II and Jor exchange the antidote for the plans for the Time Bubble, and Kal returns to the present, where he is amazed to see that Gann Artar is not in the Phantom Zone - he is the Mystery Raider!
At Gann Artar's fortress, he has fooled Superman and Jor-El the second with Green Kryptonite, and they lay dying. But the human Kal-El II is unaffected by Kryptonite, and sends Gann back into the Phantom Zone. Using Jor-El senior's formula, they restore the animals of Earth.
