19th-century England. Sebastian, the all-purpose butler of the Phantomhive family, the "evil aristocracy" who handle Queen Victoria's clandestine affairs, is secretly a demon. Under a contract with Ciel, the solitary young head of the family who faces his cursed fate, Sebastian works in Ciel's shadow, resolving incidents in the underworld. One day, a letter arrives from the Queen requesting an investigation into the whereabouts of Derrick, the son of Duke Clemens, her cousin, who hasn't returned home since last summer. Sebastian and Ciel infiltrate the prestigious boarding school Derrick attends, posing as a teacher and student. What truth will the two uncover after infiltrating the closed world of the boarding school, protected by tradition and strict rules?