Justice League: Crisis on Two Earths

Lex Luthor and the heroic analogue of the Joker, the Jester, steal the Quantum Trigger device from the Crime Syndicate's headquarters. They attempt to escape after securing the device, but an alarm alerts the Syndicate to their presence. The Jester sacrifices himself with a bomb to allow Luthor a chance to escape, killing several key characters in the process.

Luthor activates his dimensional travel device, escaping to the Earth of the Justice League. The Syndicate members begin to pursue him, but Luthor's device delays them. Luthor's arrival sparks suspicion and prompts the League to investigate his origins and motives.

Superman's x-ray vision confirms Luthor's alternate origin, revealing his organs indicate he is from a parallel Earth. Luthor explains that his Earth is under domination by the Syndicate, which has eliminated his Justice League counterparts and threatens to use nuclear retaliation to maintain control.

The Justice League decides to help Luthor by transporting their members to his universe. Batman opts to stay behind, working on building the Watchtower to aid in future operations. The remaining League members prepare for a mission to confront the Syndicate on Lex's Earth.

The League arrives at Lex's Justice League headquarters but faces the Syndicate, forcing a retreat. They regroup at Jester's base, formulating plans to attack Syndicate targets and capturing Ultraman, the evil counterpart of Superman.

President Slade Wilson orders the release of Ultraman, citing the necessity to prevent chaos. This decision outrages Lex and the League, but Wilson explains it is a strategic choice to save millions of lives. Later, Wilson's daughter Rose shows concern over her father's actions.

J'onn J'onzz reads Rose Wilson's mind during an assassination attempt, revealing her fears about her father's decisions. He later saves her during an attack, and the two begin to fall in love, adding a personal stakes element to the conflict.

Owlman, Batman's evil counterpart, builds the Quantum Eigenstate Device (Q.E.D.) with the destructive potential to wipe out entire worlds. He reveals his obsession with choosing to destroy Earth-Prime, believing it would erase all alternate realities and give his actions true meaning.

The League fights the Syndicate on their moonbase, with heroes facing off against their evil counterparts. Owlman activates the Q.E.D. and heads towards Earth-Prime, planning to destroy it and the entire multiverse. Batman deduces which universe is Earth-Prime and prepares a daring plan.

Owlman attempts to detonate the Q.E.D. on Earth-Prime but is outwitted by Batman. In a last act of madness, Owlman chooses to stay and activate the weapon, dying in the explosion and declaring 'It doesn't matter.' His death prevents the destruction of Earth-Prime.

With Owlman's plan thwarted, the remaining Syndicate members are captured by U.S. Marines led by President Wilson. The League is thanked for saving their world and returns to their original dimension, with Wonder Woman keeping the stolen cloaked plane as a memento.

Recognizing the threat of spread-out superhero forces, Batman considers expanding the Justice League. He opens the invitation to additional heroes like Aquaman, Red Tornado, Black Lightning, Firestorm, and Black Canary to strengthen their global presence, preparing for future threats.