New England, 1892. Young adventurer Abigail Rook gets a job as an assistant to young detective R.F. Jackaby, a researcher of unexplained phenomena. Jackaby has an unusual gift - he can see fantastic creatures living in the city under the guise of ordinary people and animals. Abigail's talent for noticing ordinary but important details makes her the ideal assistant to a paranormal detective. Abigail's first day on the job begins with a terrible incident: a serial killer appears in the city. The police consider him a common criminal, but Jackaby is sure that he is an inhuman creature. The mystical investigation begins!