Oz Vessalius, heir to one of the four great duke houses, is cast into the Abyss during his fifteenth birthday ceremony, when the Baskerville clan condemns his very existence as a sin. In that nightmarish prison dimension he meets Alice, a powerful Chain known as the B-Rabbit who has lost her memories, and forges a contract with her to escape. They surface ten years later into a world that has moved on without him, now under the watch of the Pandora organization.