Alone and newly arrived in New Fiddleham. 1892, Abigail Rook finds work as the assistant to R. F. Jackaby, an investigator of the unexplained with the ability to see supernatural beings. On her first day, Abigail finds herself in the midst of a thrilling case: A serial killer is on the loose in New Fiddleham. The police are convinced it's an ordinary villain, but Jackaby is certain the foul deeds are the work of the kind of creature whose very existence the local police - with the exception of a handsome young detective named Charlie Cane - seem adamant to deny.