On the Spaceship,Starro the Conqueror & his Gladiator,Despero plan to invade earth when they get a distress signal from here.
At Gotham,Batman stops the robbers,who had Alien Starfishes on their faces. He contacts Clark and suggests that they need a team. They found 4 other heroes who fought off the invasion:The Flash,Aquaman,the Green Lantern,& Wonder Woman. They decide to work together along with J'onn J'onzz,who is also called Martian Manhunter. They search for the Source and confronts Starro & Despero,who are feeding the People's conscious to the Giant. Despero reveals that the Conqueror's real name is Cobi from the planet,Hatoreian and he was in control by the Giant.
The Heroes battle them. The Flash quickly free the Mind Controlled people & Green Lantern gets them to safety. Martian Manhunter manage to free Cobi & defeats Despero. The Giant has finally awoken.
They fought against it. Superman blasted one of his limbs with his Heat Vision.
Batman uses the smoke grenade to weaken Starro,allowing Aquaman to hurl the Trident at the Giant's eye,killing it. Cobi thanked the Heroes and return home while Despero was taken into custody by the Guardians. The People congratulates the Heroes,who are called "The Justice League".
Mid-Credits:
Bruce takes Starro's severed limb that was shrunk to Wayne Manor where it regenerate into a new body.
Post-Credits:
Lex Luthor went inside Zod's Ship where he heard a voice saying "Hello,Luthor.
I've been expecting you".