Queen Victoria of England has ordered her loyal watchdog, 13-year-old Earl Ciel Phantomhive, to investigate a series of suspicious deaths in southern Germany. Across multiple villages, all the victims have one thing in common: they had entered the so-called Werewolves' Forest right before they developed strange deformities and subsequently died. The rumors put blame on a "witch's curse," the nearby villagers' firm belief based on old folklore.

Unconvinced that anything truly supernatural is at play, Ciel and his contracted demonic butler, Sebastian Michaelis—along with the rest of the Phantomhive servants—come across an isolated village in the Werewolves' Forest. Its residents are only women, hostile toward the outsiders and serving a young girl with emerald eyes and bound feet, Sieglinde "Green Witch" Sullivan. Ciel and Sebastian investigate to uncover the truth, but as they soon fall victim to the curse themselves, it appears that there is more to the local myths than meets the eye.