“THE CREATURE FROM THE END OF TIME!” A giant box appears in Toronto, and the Challengers, accompanied by Swamp Thing and Deadman, investigate. When Deadman tries to enter the box, it opens and releases a monster. After they kill the monster, the Challengers haul the box and carcass to Challengers Mountain, where tests indicate the box is from the future. The heroes fly to Rip Hunter’s desert lab, which appears abandoned. Swamp Thing pushes a button and Rip’s Time Sphere appears with a skeleton inside. They use the time sphere to travel to 12,000,000 AD. Amidst crumbling ruins, they are surrounded by future-men and Rip Hunter in rags and a crown.
Red Ryan in a jealous rage picks a fight with Rocky. Deadman, Swamp Thing and June break it up, but Ryan quits the team.
Meanwhile a giant box appears in Toronto. The Canadian authorities are incapable of dealing with it, so they call the Challengers for help.
In trying to enter the box, Deadman accidentally sets free a giant monster, and it's up to the Challengers to save the city!