Spinning out of Absolute Power and the DC All In Special, the terror of the Darkseid shockwave has cascaded across the DC Universe... tearing open the very fabric of time and space itself! Only one band of super-scientists have the right stuff to challenge the fate of a universe... enter: THE CHALLENGERS OF THE UKNOWN. Alongside the Justice League -- where the Challengers run day-to-day operations for the massive Watchtower base in orbit above Earth -- Ace Morgan, June Robbins, Prof Haley, Red Ryan, and Rocky Davis must team with Superman, Batman, Wonder Woman, and the rest of the League to seal the rifts that threaten the galaxy. But a mysterious foe from the Challengers' past lurks in the shadows, and its connection to the godshock will put the DCU on borrowed time!