Following the death of Superman, the world mourns the loss of its beacon of hope. Sensing a newfound vulnerability, an ancient and powerful enemy, Steppenwolf, arrives on Earth with an army of parademons in search of three powerful artifacts known as Mother Boxes. Batman, aware of the impending threat, seeks out other meta-humans to form a line of defense against the invasion. He joins forces with Wonder Woman, and together they recruit The Flash, a speedster; Aquaman, the heir to the underwater kingdom of Atlantis; and Cyborg, a young man who has been transformed into a cybernetic organism after an accident involving a Mother Box.

As the newly-formed group struggles to come together, they grapple with their own demons and the weight of being the planet's last line of defense. Each member confronts their past and their fears, realizing that their individual abilities are amplified when united as a team. They also learn more about the significance of the Mother Boxes and the existential threat that Steppenwolf poses, not only to Earth but to the entire universe. Meanwhile, without Superman, humanity's hope wanes, and the team must find a way to overcome their own internal conflicts and face the looming onslaught with a united front.