Parademons have been kidnapping and experimenting on humans in Gotham City, prompting Batman to investigate. He encounters Green Lantern while both are tracking the mysterious alien creatures. The two heroes discover a mother box, a powerful alien computer, which leads them to believe an invasion is imminent. Superman joins them after an altercation, and with the help of investigative reporter Lois Lane and STAR Labs scientist Silas Stone, they uncover that more mother boxes are appearing around the world. Meanwhile, young football star Victor Stone gets caught in an explosion caused by one of these devices, leading his father, Silas, to use the alien technology to save him, transforming Victor into Cyborg.

Simultaneously, Wonder Woman is visiting Washington D.C. for diplomatic purposes but is soon embroiled in the conflict when a mother box activates nearby. The alien invasion begins in earnest, with legions of parademons attacking major cities. Flash and Shazam join the hastily formed team of heroes to combat the threat posed by Darkseid, a powerful tyrant who seeks to conquer Earth. As they face off against Darkseid’s forces, the heroes must learn to work together despite their differing methodologies and personalities to protect humanity from certain doom. The newly formed team’s synergy and determination become the Earth's best hope against the extraterrestrial threat.