In the dark caverns, an ancient threat is stirring... The last mers of Atlantis have been forced to flee their home. Now they must try to survive amidst the perils of the open ocean. But the sea hides worse dangers than ships, sharks and storms, and not all the merpeople's enemies are human. The spy-birds are flying. The hunters are gathering. And far, far away, in a labyrinth under the waves, the lost treasures of Atlantis wait for the mer who will use them to bring peace... or war. So continues the epic tale of Poseidon's Children, as they come face to face with a deadly foe, and are forced to make a deadly choice.