In a flashback to his childhood, Bruce Wayne runs from his parents' funeral.
He falls into a cave, where a circling vortex of bats elevates him back to the surface.
- In the present, eighteen months after his cataclysmic battle with General Zod in Metropolis, [a] Superman has become a controversial figure.
- Bruce is now a billionaire who has operated in Gotham City as the masked vigilante Batman for twenty years. Having witnessed the battle in person,
- he sees Superman as an existential threat to humanity.
Clark Kent, Superman's civilian identity, seeks to condemn Batman's form of justice in Daily Planet articles. Bruce learns that Russian weapon trafficker Anatoli Knyazev has been contacting LexCorp mogul Lex Luthor. Luthor attempts to persuade Senator June Finch to allow him to import kryptonite discovered in the aftermath of Zod's terraforming attempt, so that it can be used as a deterrent against future Kryptonian threats. She declines, but Luthor makes alternative plans with Finch's subordinate, who grants him access to Zod's corpse and the Kryptonian scout ship. [b]
Bruce attends a gala at LexCorp to steal encrypted data from the company's mainframe, but antiquities dealer Diana Prince steals it first; she later returns it to Bruce. While decrypting the drive, Bruce dreams of a postapocalyptic world where he leads rebels against an evil Superman. He is awakened by an unidentified person, appearing through a portal, who tells him that Lois Lane is "the key" and urges him to find "the others" before vanishing. [c] The decrypted drive reveals Luthor's files on several metahumans across the globe. One is Diana, who appears in a photo from World War I. Wayne contemplates weaponizing the kryptonite to go to war with Superman.
A widely publicized congressional hearing, led by Finch, is held to question Superman's actions against Zod. A bomb smuggled in by Luthor detonates, killing everyone present except Superman. Superman blames himself for not detecting it in time and self-imposes exile. In response, Batman breaks into LexCorp and steals the kryptonite. He builds a powered exoskeleton, a kryptonite grenade launcher, and a kryptonite-tipped spear. Meanwhile, Luthor enters the Kryptonian ship and accesses its vast database of technology.
Luthor lures Superman out of exile by kidnapping Martha Kent, Clark's adoptive mother, and Lois, who he pushes off the LexCorp building. Superman saves Lois and confronts Luthor, who reveals that the distrust between Batman and Superman was manipulated. Luthor demands that he kill Batman in exchange for Martha's life. Superman tries to explain this to Batman, who instead attacks and eventually subdues him using a kryptonite gas. As Batman prepares to deal the final blow using the spear, Superman pleads with him to "save Martha" – the same name as Batman's mother. Batman hesitates in confusion, as Lois arrives and explains what Superman meant. Coming to his senses, Batman locates and rescues Martha.
Luthor executes his backup plan: unleashing a monster genetically engineered using DNA from both Zod's body and his own. [d] Diana joins Batman and Superman in their fight against the creature. Superman realizes its vulnerability to kryptonite and fatally impales the creature with the kryptonite spear. Superman, already weakened by kryptonite exposure, is fatally wounded by the creature before it dies.
Following Luthor's arrest, Batman confronts him in prison, warning him that he will always be watching. Luthor gloats that Superman's death has made the world vulnerable to powerful alien threats. A memorial is held for Superman in Metropolis, while Bruce and Diana attend a funeral for Clark, who was also declared dead. Martha gives Lois an envelope containing an engagement ring from Clark. Bruce tells Diana that he regrets failing Superman and asks for her help in forming a team of metahumans to protect Earth in Superman's absence. As they leave, the dirt atop Clark's coffin levitates.
