Aquaman discovers what's been raising Atlantis: an alien ship guarded by the dragon-like Tiamat, an ancient god. To defeat it, Aquaman must become one with the ship as the whole city breaks the surface of the water, creating tidal waves throughout the globe!
As Aquaman, Mera, Dolphin, and A.J. stare at Attlan's face through the viewing device, Aquaman is able to convince he father to rescue them, making a portal to draw them through. However upon arrival in the dimension, A.J. begins aging rapidly due to his being born in the Netherspace causing Mera to throw him back through as well as herself with Aquaman failing to stop her, much to his horror. Aquaman then realizes where Atlan has transported them to the sentient area underneath Poseidonis. While Aquaman realizes this place holds many answers Posiedonis once again begins to rise, while in the same area a monster realizes this to be Atlan's doing. The creature Tiamat then scoffs at Aquaman's assertion that his dreams have prepared him to come to this place, before leaping into battle, until Tiamut's very ship turns against it as it had long learned a love for humanity. The ship ultimately fulfills a ancient prophecy when it raises the very dome of Poseidonis above the ocean.
Meanwhile Admiral Strom has shown the threat Thanatos recorded prior to his death to several other top ranking military officials .While in the sacred tunnels where they come along an ancient casing of shells and seaweed which confounds even Vulko himself. Ultimately the casing is revealed to contain Kordax himself,who vows to rule the world.