With the imminent destruction of Krypton looming, Jor-El desperately seeks a safe haven for Krypton's populace. Jor-El's research into parallel dimensions leads him to discover the Phantom Zone. Jor-El projects himself into the Phantom Zone, finding it to be a horribly oppressive environment. In his haste, Jor-El failed to connect the projector properly and finds that, to his horror, he is trapped within the Phantom Zone. Jor-El's wife, Lara Lor-Van, intuitively sensing his distress, makes the necessary connections to the projector, and pulls her husband from the Phantom Zone. Lor-Van is outraged that her husband would take such risks. Though the Phantom Zone proves not to be Krypton's salvation, it ultimately serves Krypton as a prison for the most heinous of criminals. Men like Jax-Ur, who's unauthorized rocket experiments resulted in the destruction of Krypton's moon, Wegthor, along with it's entire populace. Va-Kox, who mutated Krypton's fish into horrific monsters. Dr. Xadu, for his nightmarish experiments on Kryptonian citizens. Faora Hu-El, for the brutal murder of 23 men. Nam-Ek, for killing the Rondor, a protected species on Krypton. The most infamous of all, though, was General Zod, a military leader-turned-dictator, who raised an army of inorganic "men" to seize power, at Fort Rozz. Jor-El personally sentenced his cousin, Kru-El, to the Phantom Zone. Kru-El had built a cache of forbidden weapons, but it was the shame he brought to the House of El that earned Jor-El's ire. The Phantom Zone, though, was not just a depository for Krypton's most wanted. In truth, the Phantom Zone was the manifested collective consciousness of two entire civilizations, both of which died violently when their worlds collided. On some level, that consciousness was aware of the Kryptonian's intrusion into it's being.
Led by General Zod, several of the Phantom Zone inmates attempt to telepathically influence Jor-El into releasing them, at a time when Jor-El is mentally weak. His wife prevents him from activating the Phantom Zone Projector. To prevent further such escape attempts, the Phantom Zone Projector, along with all of Kru-El's weapons, are rocketed into deep space. In the Valley of Juru, the wizard, Thul-Kar, finds that he has arrived too late to join his order in ritual suicide. To preserve his life, and escape the destruction of Krypton, Thul-Kar mystically transports himself into the Phantom Zone. In the final moments before Krypton's destruction, Jor-El launches his only son, Kal-El, in a rocket aimed for Earth. Thul-Kar's sorcerous abilities allow him to make direct contact with the consciousness of the Phantom Zone, called "Aethyr". Thul-Kar creates a fetish of the Bizarro World, which Aethyr seems to inhabit. At that moment, the true Bizarro-World implodes, collapsing into a white hole. As the Bizarro World fetish crumbles in Thul-Kar's hands, Aethyr seems to have undergone a change. The Phantom Zone consciousness is suddenly desperately in need of moving it's essence into the physical world. On the fifth dimensional world of Zrff, Mister Mxyzptlk is sentenced to a null zone, for the crime of bigamy. Thul-Kar reaches out to Mister Mxyzptlk, in the Null Zone, offering him freedom and revenge on his enemies, in exchange, momentarily, for control of his mind and powers. Mister Mxyzptlk agrees. Thul-Kar forges a link between the Aethyr and Mister Mxyzptlk, giving Mister Mxyzptlk an enormous boost in power. Immediately, the fifth dimensional imp breaks free from the null zone. MIster Mxyzptlk exacts his revenge on his jailers by destroying their city. Lana Lang and Clark Kent are in the middle of a news broadcast, when the severed head of Bizarro crashes down upon the news desk, announcing the presence of Mister Mxyzptlk.
Kent rises to meet the challenge, as Superman. Mister Mxyzptlk draws a city-sized meteor of pure Kryptonite down on Metropolis. Despite the danger, Superman smashes into the meteor, shattering it into millions of pieces. Only when corpses begin falling from the sky does Superman realize that he has just destroyed Argo City. As a debris cloud of Kryptonite settles over Metropolis, Superman collapses. With Mister Mxyzptlk as it's anchor, the Aethry completes it's journey into the material world. The instant it does so, the Phantom Zone ceases to exist. All at once, the worst of Krypton's criminals descend on Earth. Though he has been completely consumed by the essence of the Aethyr, MIster Mxyzptlk's personality is still dominant. In revenge for what Thul-Kar has done to him, Mister Mxyzptlk, acting through the Aethyr, begins to reabsorb the Kryptonian escapees, starting with Thul-Kar and Nam-Ek. Superman awakens on the Moon. With his telescopic vision he sees General Zod, and the rest of the Kryptonian villains, razing Washington D.C. Superman beats General Zod into unconsciousness, before taking on the other escapees. Though he fights valiantly, Superman is eventually overwhelmed by their greater numbers. Faora Hu-El is just about to murder the Man of Steel when Aethyr/Mister Mxyzptlk reabsorbs her into itself. Having attained Godhood, Aethyr/ Mister Mxyzptlk departs Superman's dimension, along with all the newly imprisoned Kryptonian criminals. With the destruction of Argo City and Metropolis, Mister Mxyzptlk feels his victory over Superman has been so total, that he need not ever vex the Man of Steel again. Crestfallen at his utter defeat, and grieving the loss of the two cities, Superman is left to cope with the horror of Mister Mxyzptlk's final victory.