After Oz Vessalius plummets into the hellish Abyss on his 15th birthday, he emerges ten years later and finds only a short time has passed for him. Having forged a contract with a Chain named Alice—a being from the Abyss—he now sets out to unravel the secrets behind why he was sent there and his own past.

The path towards his destination is not clear. For Oz and those he meets, it is a caucus race—a race without end. Between the various dukedoms in the past and present, many stories come to light. Whether tales of realization or woe, Pandora Hearts: Caucus Race follows many of the side characters of the original Pandora Hearts, delving into their hidden lives and motivations.