A young man is called through the moonlight vision of a mermaid to a Hidden Land beneath the sea. There he finds a land of myth and mystery, of high adventure and lurking danger. At the heart of the danger is a powerful demon who entered that world with an intent to dominate it -- and the home world of the young man as well. The young man also meets a beautiful princess, and the pair, with a few loyal allies, engage in mortal combat against the evil demon. In the course of his adventures, our hero finds life, love and, above all, himself.