The Justice League escorts Lex Luthor and his remaining villain allies into the Hall of Justice and wonders how they survived the explosion. Lex explains that Sinestro created a power ring bubble around the piece of debris they took shelter on. An inhabitant of New Genesis noticed the explosion and came to investigate, and they knocked him out and took his Mother Box. Lex wants Brainiac back after Darkseid took it from him, but the other villains note that Darkseid plans to conquer Earth and want to help. The heroes plan to take them into custody but they're interrupted when Mr. Terrific on the Watchtower notifies them that boom tubes are opening up above major cities across the Earth. Darkseid's invasion force of parademons arrives and Mr. Terrific alerts all Justice League members of an Omega level alert. They engage emergency teleporters and teams of heroes begin to beam down to Earth.
Superman and the others prepare to lock up the heroes but the villains insist they'll fight back unless they're allowed to help. Batman concedes they'll need as many bodies as possible and Lex points out the heroes are there to get revenge on Darkseid and after that, it's back to business as usual. They team up the villains with heroes as Mr. Terrific confirms that Darkseid's command vessel is above the Daily Planet
and Superman insists on going after it.
Parademons attack the White House only to discover Shayera, Commander Steel, and Atomic Skull waiting for them. The Flash, Giganta, and Green Lantern take on the invasion forces in Paris, while in China, Star Sapphire, Wonder Woman, Vigilante, and Shining Knight fight parademons. Dr. Light, Green Arrow, Black Canary, and Bizarro oppose the invaders in Rome, while Sinestro battles Darkseid's troops in Paris. Hawk, Dove, the Creeper, Captain Atom, and the Question do what they can in Metropolis, while in the Middle East, Toyman disposes of opponents with a toy Nerfgun with exploding shells. In London, Hawkman, Stargirl, S.T.R.I.P.E. and Killer Frost struggle against overwhelming odds.
Superman, Batman, and Lex Luthor teleport to the Daily Planet
and face an onslaught of demons. They obtain a momentary lull only for Darkseid to descend, still covered in the Brainiac technology. He tells Superman that he is responsible for everything that happens to Earth since the Kryptonian drew Darkseid's attention to the planet. Lex attacks him first but Darkseid immobilizes him with an energy field, then tosses him over the side of the building. Batman leaps after him, catches him, and fires a grappling hook upward. They swing into an office building, stunned. Darkseid points out he's more powerful than ever and smashes the Daily Planet
globe onto Superman, driving it and the hero through the building below all the way to the ground floor.
In China, Star Sapphire is badly hurt but Shining Knight flies to her rescue and catches her before she hits the ground. On the Great Wall of China, an elderly Chinese man tells his wife he has to help and she says she understands as he runs off.
In Tokyo, Steel and Mr. Terrific realize that the invaders are setting up tapping machines to tap into the Earth's core and unleash molten lava. Mr. Terrific coordinates the heroes to target the machines. In Washington, Shayera attacks the machine but takes a spear to the wing, pinning her to the machine. Commander Steel uses a shield to decapitate her attacker and buy her enough time to free herself and destroy the machine with her Nth metal mace. Atomic Skull grabs her and gets her to cover as the machine blow up.
In Paris, Flash suggests that Green Lantern throw their machine into the sun. The Flash creates a giant trench around the machine and Green Lantern creates a giant catapult to launch it into a battle cruiser, destroying them both.
As Wonder Woman destroys the machine in China, Darkseid grabs the stunned Superman and says he'll only die when Earth is destroyed first. However, Batman throws a Batarang into Darkseid's armored sleeve, breaking his grip, and Lex opens fire. Darkseid is unimpressed and orders his parademons to attack, but Superman recovers and knocks Darkseid flying. Above, Metron of the New Gods sits and watches.
In China, Wonder Woman sees the elderly Chinese man approaching and warns him away. The man assures her he can help and casually bats parademons away. He flies into the sky and then transforms into a Chinese dragon. He finally flies up to the Wonder Woman and reveals himself as... J'onn J'onzz. They take the battle to the parademons as elsewhere, Zatanna transforms parademons into doves and then brings down other ships with mystical lightning, while Volcana burns them with flame.
In Metropolis, Batman is out of Batarangs and explosives but turns down Lex's offer of a spare gun. Above, Darkseid catches Superman's fist and smashes him down, but Batman distracts him. Darkseid unleashes the Omega Force and Batman leaps onto a parademon, jumping away and letting it be destroyed. Batman is knocked into the rubble and Darkseid is impressed that someone avoided his Omega Force, and wonders if Lex is as agile. Lex runs and Darkseid kicks Superman down and then beats him mercilessly. He smashes Superman's back across his knee and moves in for the kill. Lex sees Metron hovering above the fray and demands that he help. Metron concedes there is one thing that might destroy Darkseid, but it's too dangerous. Lex threatens him and Metron agrees to give him what he wants. He teleports Lex away in a boom tube.
Batman leaps onto Darkseid's back to distract him but the Lord of Apokolips throws him aside. Superman manages to regain a second breath and cuts loose, informing Darkseid that he's one of the few opponents upon who Superman can truly cut loose. Superman unleashes all of his strength on Darkseid, sending shock waves reverberating through the city and sending Darkseid flying blocks away through multiple buildings. Superman flies ahead of him and smashes him straight down, leaving a massive crater. Superman asks if Darkseid has had enough and moves in, but Darkseid unleashes the Agony Matrix, causing Superman to fall to the ground screaming in pain.
Metron takes Lex to the Source Wall, behind which lies the greatest secret of the universe. Lex leaps into it without hesitation and finds himself screaming in agony at what he sees beyond.
Darkseid draws a Kryptonite knife and prepares to put Superman out of his agony. Lex arrives, wearing his business suit, and informs Darkseid that they have unfinished business. He holds up a glowing ball of energy, the Anti-Life Equation, and offers it to Darkseid. Darkseid reaches for it as Batman arrives and watches as Darkseid and Lex are enveloped in a swirling matrix of energy. Batman holds Superman back as both villains admit that the Equation is beautiful. Batman gets Superman to safety as waves of energy wash across Metropolis and beyond. When the energy dies down, there is no sign of Lex or Darkseid.
As the heroes and villains reassemble, the parademons flee back to Apokolips through the Boom Tubes. Superman is surprised that Lex sacrificed his life, but the others figure that both villains will be back some day. Wonder Woman suggests locking up the villains but Batman decides to give them a five-minute head start. The villains make a hasty exit except for Giganta, who stops long enough to kiss the Flash. J'onn calls his wife and assures her he'll be home soon, while Superman ribs Batman about giving the villains a head start. The heroes depart, with the founding members bringing up the rear.