Spoiler Warning for Superman II
Before Krypton's tragic implosion, convicted insurrectionists General Zod (Terrance Stamp), Ursa (Sarah Douglas), and Non (Jack O'Halloran) disable a security guard maintaining a crystalline matrix table. The lead general then removes a glowing red spire from the table and destroys it, with the thunderclap resonating throughout the alien city, and sets off a trap that ensnares the three brigands. The red spire's destruction was an act of pure treason, and for this and the myriad of other crimes that they committed, they are sentenced by Jor-El (Marlon Brando) and the Krypton council of elders to an eternity inside the Phantom Zone.
On Earth, Clark Kent (Christopher Reeve) arrives at The Daily Planet for work on an article. He then talks to his editor-in-chief Perry White (Jackie Cooper), who's working on their latest cover story. Perry tells Clark that a small group of random terrorists is currently holding hostages at the top of the Eiffel Tower in Paris, threatening to detonate a hydrogen bomb. Perry had already sent his ace reporter, Lois Lane (Margot Kidder), to Paris on a Concorde jet to get the story. Kent leaves the Planet building, ducks into an alley, and secretly transforms into Superman, flying off towards Paris.
At the Eiffel Tower, Lois was able to sneak past the security and stow away on the bottom of the elevator that brings the innocent hostages down from the top. When a French commando team determines that the hostages are safe and they believe the terrorists have taken the bomb out of the elevator, they cut the power and destroy the chain drive. The elevator begins to plummet fast, taking the bomb and Lois with it. Superman arrives and stops the car, helping Lois off the bottom. He then flies the elevator out into space and past the Moon, where it then explodes in space.
The Phantom Zone is nearby to where the car detonated, where it was then cracked by the shockwave. The three criminals were finally freed, finding themselves with superpowers granted by the yellow light of Earth's sun. After attacking some human astronauts on the moon and the small town of East Houston, Idaho, the three then fly towards the White House and force the President of the United States (E.G. Marshall) to surrender to Zod during an international television broadcast. When the President warns Zod that Superman will stop them, Zod announces his demand for Superman to come and "kneel before Zod!"
Before Zod's arrival, Clark Kent and Lois Lane are sent on assignment for the Daily Planet to cover an article on Niagara Falls. Lois becomes suspicious that Clark is Superman and tries to lure him into revealing his identity by throwing herself into the Niagara River gorge downstream, but Clark manages to save her with the subtle use of his powers. That night, Clark accidentally reaches into the room's fireplace to recover his glasses after he trips; when Lois discovers that his hand isn't the slightest bit burnt by the fire, Clark is forced to admit he is, in fact, Superman.
Superman goes to take her to his Fortress of Solitude near the North Pole, showcasing the many traces of his past stored in certain energy crystals within the Fortress, one of which is the very green crystal that birthed the whole Fortress and operated Superman's contact with his long-deceased Kryptonian birth parents. Lois accidentally misplaces the green crystal under her purse. Superman, after talking to a hologram of Lara-El (Susannah York), his mother, eventually decides to transform to make himself a human being, which involves exposing himself to the red Kryptonian sunlight. This is all in the chance to become romantically closer to Lois, despite Lara-El's many warnings. The transformation process destroys many of the energy crystals, all except the green crystal, lying a considerable distance away. After spending a romantic night together, the two then return to populated areas by conventional means.
In a remote truck stop, Clark becomes the unfortunate target of a brash, bullying truck driver, who starts beating him up. This causes Clark to realize that he's just as vulnerable as a human, shocked by the sight of his face bleeding. Suddenly, the two reporters saw a live broadcast of Zod with the U.S. President, demanding that Kal-El reveal himself and Kneel Before Zod. Realizing that humanity cannot fight Zod by themselves, Clark decides to return to the Fortress of Solitude to try to reverse his human transformation. His long hike to the Fortress is nearly impossible, so by the time he arrives, he admits to his father that he made a grave mistake and that the Earth he loves so much is now in more danger than ever before. As he's ready to give up, he notices the green crystal lying nearby.
Lex Luthor (Gene Hackman), who managed to escape prison thanks to Eve Tessmacher (Valeria Perrine), was able to track down the Fortress using an alpha wave detector, and infiltrated the Fortress before Superman and Lois could arrive, learning Superman's connection to Krypton through Lara-El's message. The crystal of Superman's mother of Superman's connection to Jor-El and General Zod. He traces Zod to Washington, D.C., and offers to lead Zod to Jor-El's son in exchange for control of Australia. Accepting his offer, the three Kryptonians are directed by Luthor to the offices of the Daily Planet where they abduct Lois. Though Zod is initially disappointed, Luthor convinces him that any threat to Lois will bring Superman to her aid.
Superman arrives, after having reversed his transformation process, and attempts to fight the powerful criminal trio. The battle wages over much of Metropolis with Superman courageously holding his own until Zod realizes Superman cares for the innocent humans and begins harming them to take advantage of that love. To protect the citizens, Superman starts flying off in retreat. Zod declares his victory but Luthor scoffs until he reveals that he knows the location of the Fortress of Solitude. Zod, Ursa, and Non fly to the Arctic, taking Luthor and Lois with them.
At the Fortress of Solitude, Superman attempts to lay down one last trap to stop Zod but fails and stops his fight with the three when they threaten to kill Lois Lane. Knowing the kind of threat the three pose to all of Earth, Luthor listens as Superman tells him to try and trick them all into the crystal chamber that will transform them into humans. Zod catches on and forces Superman to enter the chamber himself. Luthor himself initiates the process by placing the green crystal in the remaining control panel. While Superman is in the transformation chamber, the rest of the Fortress begins getting bathed in a bright red light. Zod demands that Superman kneel to him and take his hand. Superman slowly but surely crushes Zod's hand in his and throws him into the eternal crevice below. Luthor soon begins to realize that Superman had actively reversed the power of the chamber to protect him and transform the criminals. Non, unable to fly, falls into the pit and Lois punches Ursa, who suffers the same fate as her comrades.
Superman then returns Lex to the police, despite the criminal's pleas that he was in on the hero's plan. Superman then returns Lois to her house. Back at the Daily Planet the following day, Clark kisses Lois, using his powers of telepathy to memory wipe Lois' of all the events surrounding Zod's arrival on Earth, including her knowledge that Clark and Superman are one and the same. At the truck stop where he was beaten up by the bullying driver, Clark takes karmic revenge on the bullying truck driver who assaulted him.
Superman then starts repairing all the damage caused by Zod, which involves replacing the flag on top of the White House, and promises the President that never again will he abandon his duty as a hero.
