A secretive widower hires a governess for his children, a willful boy and impressionable girl. Strange occurrences and the governess's curiosity lead her to unlock the secrets of the mysterious and uninhabited brownstone next door.
Governess Elizabeth Howard fears that David, both her widowed employer and the man she loves, could be the strangler that's stalking women in the small New England town where they live. So do the police. His little son Barnaby knows who the killer is but won't tell. Elizabeth becomes convinced that the killer is now stalking her as well.
