The Dawn of Man

Anthro the Cave-Boy leads a herd of mammoths away from the village of the Bear Clan tribe. After falling from atop one of the great beasts, he peers through the underbrush where he sees an image of a great futuristic city. He shakes his head and when he looks again, the image is gone. In addition, the herd of mammoths that he had corralled is likewise missing.
30th Century Earth

Members of the Legion of Super-Heroes discover the displaced mammoths stampeding through Plaza Square in Metropolis. Colossal Boy attempts to scoop them up into his giant arms, but they suddenly disappear.
Earth One – July 1985

In Gotham City, the Joker murders film mogul, Harold J. Standish. Batman crashes through the window and attempts to disarm the villain, but the Joker keeps him at bay with an adhesive shooting flower. Suddenly, a distraught image of the Flash appears before them, warning about the end of the world. Batman tries to talk to the Flash, but he disintegrates before his eyes.

On board the Monitor’s satellite, the Monitor warns his assemblage that a wave of antimatter energy is sweeping through the Multiverse consuming entire realities. He has established certain devices throughout the various realities designed to halt the antimatter wall. He requires the heroes to travel to each reality and activate each of the devices. Nobody truly trusts the Monitor, but they realize that they have little choice but to heed his warnings.

Superman of Earth-Two, King Solovar and Dawnstar travel to Earth-AD, the world of Kamandi. They find the adventurer, Kamandi, scaling the side of an immense golden tower. The heroes realize that this is of the devices that the Monitor spoke of. A horde of Demon-Shadows arrives to sabotage the tower, but the heroes manage to drive them away.

Arion, Obsidian and the Psycho-Pirate arrive in ancient Atlantis. Suddenly, Pariah arrives, but quickly falls sway to the Psycho-Pirate’s emotion manipulation. Arion turns his power against the Psycho-Pirate and frees Pariah of his influence. Psycho-Pirate suddenly disappears and rematerializes in a darkened room. A deep voice bellows forth to him, commanding him to follow his every order. The Psycho-Pirate, terrified by this mysterious individual, meekly complies.

Meanwhile back on the Monitor's satellite, the Monitor asks Harbinger to retrieve Alexander Luthor from his nursery. Harbinger is shocked to discover that Alex, formerly an infant, is now the age of a young toddler. Suddenly, the dark influence of the Demon-Shadow takes control of her, commanding her to betray the Monitor.