Moanna Morgan went to the ends of the Earth to find her brother – she found the end of the world. The Tethys Federation is under attack. For ten years there has been peace. For ten years, the Tethy-ans believed that they alone ruled under the waves. They were wrong. Beyond the Frontier, hostile forces are preparing for war. Pioneers and Colonists are afraid. Tensions are running high. Old divisions have never healed. Scattered throughout the Colonies, the seeds of destruction have already been sown. The end is only a matter of time. The Sunken City will stop at nothing to protect its secret. And hiding out in Aqua Incognita is the one person who can save them all…