Decaying corpses of powerful sirens float in the sea, forming a grisly trail toward the horror that killed them. Mermaids whisper about a new threat in the ocean, a menace that imperils all the denizens of the waters, from Swerighe, to Alkebulan, to all the undiscovered seas. Charlotte and her troupe, searching for clues, hear whispers of a secret treasure that might be connected to the siren deaths. An aged merman who has traveled farther than any other, reveals to them the tale of a strange, strange land: "There is a faraway land, full of steep mountains, and dangerous creatures. The forest surrounding the tallest mountain is home to a multitude of dread monsters, each more terrifying than the last, who hunger for the flesh of unsuspecting travelers foolish enough to venture into their realm. At the apex of this tall peak, which rises twenty thousand feet, past deadly glaciers and a river of fire, is a sanctuary watched over by a forgotten order of mystics skilled in the art of battle and devastation. In the rear of the sanctuary is a passage that leads into the mountain, and deep into the heart of the Earth. At its end are catacombs guarded by a beast so dreadful that minds will go mad at the sight of it. The door to the catacombs can only be accessed by defeating the beast that guards it. Inside, concealed by a hideous shroud and an ancient poison, lies the lost treasure of El Dorado."