In the wake of Superman's death, the world is left vulnerable and mourning. Sensing a newfound opportunity, an ancient and powerful menace known as Steppenwolf returns to Earth with an army of parademons in search of three mysterious artifacts called Mother Boxes. These alien devices, hidden across the planet, have the power to destroy worlds and remake them in the image of Steppenwolf's desolate homeland. Realizing that the coming battle is beyond any one hero's ability to fight alone, Bruce Wayne enlists the help of Diana Prince to form a team of metahumans capable of standing against this intergalactic threat.

Bruce Wayne, as Batman, and Diana Prince, Wonder Woman, embark on an urgent recruitment mission. They seek out Arthur Curry, who possesses aquatic abilities and is heir to the throne of Atlantis; Barry Allen, a quirky young man with superhuman speed; and Victor Stone, a former athlete who, after a tragic accident, has been transformed into a technologically advanced being known as Cyborg. Together, these heroes attempt to put aside their personal struggles and differences, forming an unprecedented league of heroes. But as they try to come together and learn to work as a unit, Steppenwolf's advance heralds the approach of a catastrophic event that endangers the entire world, highlighting the urgency of their newly founded alliance.