New England, 1892. Young adventure seeker Abigail Rook takes a position as assistant to the young detective R. F. Jackaby, an investigator of unexplained phenomena. Jackaby has an unusual gift—he can see fantastic creatures living in the city disguised as ordinary people and animals. Abigail’s talent for noticing ordinary but important details makes her the perfect assistant for a paranormal detective.
Abigail’s first day on the job begins with a terrifying incident: a serial killer is announced in the city. The police consider him an ordinary criminal, but Jackaby is convinced it is a non-human creature. A mystical investigation begins!