19th-century England―Sebastian Michaelis, butler of the prestigious aristocratic Phantomhive family, and his 13-year-old master Ciel Phantomhive, the Queen's Watchdog, undertake dirty jobs in the underworld. On the Queen's order, Sebastian and Ciel head to Germany to investigate a series of mysterious deaths. While they search for the truth about the Werewolves' Forest where anyone who sets foot inside it is cursed to death, a horrifying curse falls upon them.