Diamond is a good mare, never wronged anyone, never cheated anyone on her prices, was always friendly. But, she wakes up chained to an upside-down cross and suspended over a strange magical circle. Her kidnapper, a changeling who loves to take the form of a mare, is a psychotic demon-summoner who is known throughout the underworld for having a deal with just about every demon lord is going to use Autumn as the latest sacrifice to summon her latest con-victim.

Something goes wrong, and her kidnapper awakes in the underworld, a land filled with nightmarish beasts, tormented souls, and demons. She meets an old soldier, and together they must find Autumn in the most powerful Demon Lord's castle to escape.

But more is at stake than they realize and the fate of all the realms hang in the balance.