Reminiscent of a broken toy box, the mystical Abyss is a terrifying realm home to monstrous creatures called Chains. Most believe it to be only a fairy tale, used to scare children who misbehave. Oz Vessalius, the cheerful and mischievous heir of the noble Vessalius family, is one such individual—until, at his coming-of-age ceremony, the mysterious Baskerville Clan arrives and condemns him to the Abyss for a sin he neither committed nor knows anything about. Oz then forms a contract with Alice, a unique Chain who can take on human form, in an attempt to escape from the Abyss.

As Oz struggles to unravel the mysteries behind his sin, the Abyss, and a tragedy from one hundred years ago, he and his companions find themselves confronted by the Baskervilles and ghosts from the past. Meanwhile, his journey back home is plagued by relentless despair.

Included one-shot: Volume 8: Pandora Hearts (pilot)