Alan Scott and Jay Garrick make a fateful decision in the wake of the annihilation of fellow Justice Society members--one that will hopefully turn the tide of battle. Plus, various heroes battle the unmasked Extant and a possessed group of Team Titans!
Waverider confronts Extant, and finds out that Extant is actually Hank Hall. Hall has absorbed the powers of Waverider at another point in his timeline. Extant dismisses Waverider and the defeated JSA, as he prepares his secret weapon.
Back on 20th century Earth, the heroes must prevent a 25th century city from colliding with its 20th century counterpart. Metron coordinates the heroes successfully, as Waverider arrives with the JSA in tow. The heroes learn of Extant’s plans, of the time rifts in the past and future, and of the final battle of the JSA. The heroes split up into two teams: one set for the past and one for the future.
Superman and Metron lead a team to the 30th century, to stop the time rift in the future. As the heroes study the rift, they are attacked by Extant’s secret weapon: the Team Titans. Unknown to everyone, Hank Hall was the secret organizer of the Team Titans, and is controlling their minds. At first, it looks like the heroes will lose. However, the Time Trapper appears, and turns the tide. We find out that the Time Trapper is really Cosmic Boy. The remaining members of the30th century's Legion of Super-Heroes go to make their last stand, and the heroes defeat the time rift, though they sacrifice Metron’s Mobius Chair in doing so.
Meanwhile, Waverider and Nightwing lead a team of heroes into the past. There, they not only face more Team Titans members, but also Extant himself. Extant, now more powerful, attacks Waverider. As the heroes fight a losing battle, Waverider sends them back to the present before all is lost. Waverider is absorbed by Extant, allowing Extant to come full circle.
While Extant regroups, Extant’s mysterious boss restarts the time rift in the future, making the heroes’ sacrifices all for naught.