Black Butler: Book of Circus (2014), directed by Noriyuki Abe and based on the manga by Yana Toboso, follows Ciel Phantomhive and Sebastian as they investigate a traveling circus linked to a series of disappearances. The story combines mystery elements with darker themes and supernatural aspects.

Från IMDB:
Ciel Phantomhive, the queen's watchdog, is given two tickets to go to a traveling circus for himself and his demon butler, Sebastian. His job is to enter the circus and look for multiple missing children that are believed to be abducted.