Three Kryptonian criminals, General Zod, Ursa, and Non, are inadvertently freed from their extraterrestrial prison in the Phantom Zone due to a hydrogen bomb explosion caused by Superman. Once liberated, they discover they have powers equal to Superman's on Earth, resulting from the same yellow sun. The trio heads to Earth with intentions to dominate it, while Superman, unaware of their release, continues his life as his alter ego, Clark Kent, and deepens his relationship with Lois Lane. Tensions in their working relationship arise, leading to a series of events where Lois begins to suspect Clark and Superman are the same person.

Meanwhile, the Kryptonian villains arrive on Earth, showcasing their superior powers and subjugating humans with ease. As they wreak havoc, Superman must face the moral and physical challenges of confronting his own kind. At the same time, his nemesis Lex Luthor escapes from prison and seeks to exploit the vulnerable Superman, using the villains for his own gain. With his enemies closing in and his dual life complicating matters, Superman faces decisions that will affect his destiny and the safety of the planet.