The thief wants riches. The knight wants justice. The warrior wants a good battle. The sorcerer wants power. Each adventurer carries a mysterious crystal sphere that will lead to a long-hidden secret beneath the sea. After the thief, Halia, discovers a crystal sphere magically protected in a crumbling castle, she meets three other adventurers with their own mysterious spheres. Arwold, the knight, bears one on the hilt of his sword. With a sphere already in his possession, the sorcerer Ahriman enlists Xarun, a brutish warrior, to steal another one from the peaceful Arboreals. The four set off on a quest to find the final sphere, assisted by a master elementalist and his apprentices. Along the way, they battle demons, dragons, and one another. And they have no idea what the spheres have planned for them at the end of the journey.