As the past and present paths of the Obsidian Age converge, Nightwing, Green Arrow, and the rest of the new JLA are forced to confront an eons-old horror. The creature born from the depths of Atlantis continues to leech the Earth of its water, proclaiming itself the ruler of the realm as it fends off the new League, which has little hope of standing up to this adversary. But when a message from the past reaches the League in the present, a green ray of hope lights the way to a very unlikely ally. Can the new JLA stand where its predecessors fell?