The film kicks off with camera phone footage capturing the heroic Clark Kent/Superman (Henry Cavill) being interviewed by two children right after one of his impressive rescues. When a curious kid inquires about Superman's favorite thing about Earth, he shares a warm smile, but the footage abruptly cuts out, leaving the answer a mystery.
Fast forward several months later, we find ourselves in the gritty streets of Gotham City. A man, played by Holt McCallany, has just pulled off a robbery, only to be confronted by Bruce Wayne/Batman (Ben Affleck) who ominously perches on a gargoyle. After a brief tussle, Batman utilizes the man’s fear to expose a menacing winged creature lurking nearby. This creature is ultimately captured but explodes, revealing three charred boxes on a wall that catches the attention of Alfred (Jeremy Irons), who monitors the scene.
Months have passed since the tragic demise of Superman, which has left a void felt by many across the globe. Martha Kent (Diane Lane) relocates from her rural Smallville home while Lois Lane (Amy Adams) grapples with a profound sense of loneliness. Meanwhile, in London, a group of robbers attempts a heist in a bank. Amidst the chaos, Diana Prince/Wonder Woman (Gal Gadot) leaps down from atop a statue, determined to thwart their evil plans. She expertly defuses a bomb intended to wreak havoc on the city's technology and valiantly protects the hostages from gunfire with her legendary gauntlets.
Bruce is soon on a mission to recruit Arthur Curry/Aquaman (Jason Momoa). He finds Arthur in a local tavern, where despite Bruce’s lucrative offer, Arthur declines to join the fight, even expressing some admiration for the mysterious vigilante known as "The Batman." Dissatisfied with this setback, Bruce turns his attention to other potential allies: Victor Stone/Cyborg (Ray Fisher) and Barry Allen/The Flash (Ezra Miller), both of whom have their own struggles.
Barry, meanwhile, visits his father Henry Allen (Billy Crudup) in prison. Henry’s despair regarding his son’s attempts to save him from a wrongful conviction adds more weight to Barry's mission to use his powers for good. On Themyscira, the Amazons guard a powerful artifact known as the Mother Box, which suddenly reacts to an unknown trigger. As Steppenwolf (Ciarán Hinds) descends with his Parademons to seize the box, a fierce battle ensues, showcasing the Amazons' bravery but ultimately resulting in Steppenwolf's success.
Back in Gotham, the stakes are raised as more ominous signs surface, prompting Bruce to reach out to Diana. They discuss the history of Steppenwolf and the Mother Boxes. Diana explains how three boxes, if brought together, could grant unimaginable power, potentially spelling doom for their world. Meanwhile, lurking in the shadows, Cyborg observes the conversation, feeling conflicted about his own place in this growing conflict.
As Bruce locates Barry's hideout, he learns the truth about Barry's identity. This realization leads Barry to reluctantly join Bruce's mission. They soon meet with Diana, and later, Cyborg manages to reach them through the Batcave's computer, although he remains skeptical about joining their cause.
In Russia, a local family hears the frightful approach of Parademons. In the midst of chaos, Aquaman comes to the rescue, but he learns that Steppenwolf is already wreaking havoc at Atlantis, where he clashes with Mera (Amber Heard), who seeks to protect their realm.
As the dynamic team of heroes becomes established—Batman, Wonder Woman, The Flash, and Cyborg—they track down Steppenwolf, leading to intense confrontations. They must not only battle Parademons to free civilians but also figure out how to reclaim the Mother Boxes. Ultimately, they devise a bold plan to resurrect Superman, believing his return could turn the tide.
Upon unearthing Superman from his grave, they successfully bring him back to life, but his newfound confusion leads to a potential confrontation with the very people he once fought alongside. Thankfully, a familiar face—Lois—is brought to him, providing the comfort he needs.
With Steppenwolf uniting all the Mother Boxes to unleash destruction, the League prepares for one final showdown. Batman leads the charge, engaging the Parademons head-on while allowing others to confront Steppenwolf. It is during a crucial moment that Superman returns, reigniting hope among the team. Together, they thwart Steppenwolf, culminating in a moment of empowerment where the unity of our heroes prevails.
As peace is restored and the heroes depart to continue their journeys, Barry finds a fresh start in a forensics role, while Bruce ensures Clark's childhood home is returned to his family. Meanwhile, Arthur embraces his royal duties back in Atlantis, and Bruce, Diana, and Alfred lay the groundwork for the Hall of Justice. Lois channels her experience into her writings, emphasizing a renewed sense of hope, just as we see Superman soaring above Metropolis, restoring faith in heroes.
> Mid-Credits Scene: Superman and The Flash engage in a friendly race, wagering that the loser will host brunch for the rest.
> Post-Credits Scene: A seemingly remorseless Lex Luthor (Jesse Eisenberg) plots his next move on his yacht with Slade Wilson/Deathstroke ([Joe Manganiello]), hinting at future confrontations and alliances.
