Leviathan

In a prehistoric age before any recorded history, a great civilization flourished with towering spires and powerful rulers. Its giant inhabitants gathered ancient weapons that had belonged to primeval forces, and in doing so released a terrible sea monster to wipe out the humans who troubled them. Those facing destruction include Herrek the Giant-Slayer, Joash, and Adah, a woman from Poseidonis. This second volume in the Lost Civilizations series continues a long conflict between the Nephilim and mankind, set before the seas covered the old world.