The story begins with an eleven-month-old in the baby crib and gets picked up by the boy and was to a man.

Boy #1: "Can we hear it again? Please?"

Boy #2: "We would love to hear it again."

Girl: "More, tell us more stories. Please?"

Boy #3: "Please, Dad?"

The man chuckled, revealing to be the man, the myth, the legend himself: Anthony Edward Stark Jr. or you could just call him: Tony Stark.

Tony: "Okay, kids. One more time, then it's off to bed. Kid, climb down from the wall."

Kevin crawls down and lands on the bed, then Tony Stark starts telling a story about the New York's Earth's Mightiest Heroes. The story begins back in New York, as a group of heroes appeared, standing in front of the Statue of Liberty:

Tony: "And there came a day, unlike any other when Earth's Mightiest Heroes were united against a common threat. The Soldier (Captain America), the God (Thor), the Knight (Iron Man), the Spy (Black Widow), the Giant (Hank Pym), the King (Black Panther), the Pixie (Janet van Dyne), the Ghost (Vision), the Archer (Hawkeye) and the Spider (Spider-Man). On that day, the Avengers were born to fight foes that no single hero could withstand time-traveling conquerors, alien invaders and masters of evil. The Avengers vanquished them all, and finally when the world is at peace. The Avengers built lives of their own. The Soldier and the Spy built lives of their own, so did the Giant and Pixie, the King and his Queen, the Spider caught the cat in his web and the God of Thunder returned to his kingdom far away from the world of men and one by one the children of the Avengers came to be. Children who would one day become a new generation of heroes. But in time, evil returned. An evil called... Ultron."

The face of Ultron appeared with his eyes and month glowing red, looking menacingly:

Tony: "Ultron wanted nothing less than total domination over the world. But the Avengers stood in its way."

Ultron is seen battling the Avengers and taking them down permanently one by one: He ripped apart Giant Man and Wasp, backhanded Iron Man like he was nothing but a bug in his way, shot a hole through Spidey's stomach and snapped Black Panther's neck. Ultron already killed off half of the Avengers with little to no effort.

Tony: "Sadly, their defeat was inevitable."

Ultron stands over the dead bodies of Giant Man, Wasp, Black Widow, Spider-Man, Captain America and Black Panther. All died by Ultron's hands.

Tony: "But before they fell, the Avengers hid their children in a faraway place. Where they would grow up safe from Ultron's grasp because the Avengers knew that as long as the children were alive there was hope. Hope for the future."

We end the flashback with the children all sleeping in their bunk beds, snoring softly. Tony smiled at the children and then, he closed the door. Then a girl in blonde wrapped her arms around a white-haired boy's torso, who sleepily opens his eyes and turned to see a girl who is still asleep. Then a boy curled a cute smile before closing his eyes and continuing drifting off to sleep.

The prologue ends with a title card:

Prologue cleared.