Through A Glass Darkly — Helen McCloy

Gisela von Hohenems joins the teaching staff of an exclusive girls' school in upstate New York, where she befriends fellow newcomer Faustina Coyle. But a climate of fear surrounds Faustina, and after several strange incidents that defy rational explanation, she is forced to resign.

Gisela asks her fiancé, detective-psychologist Dr Basil Willing, to investigate in this highly acclaimed horror-mystery with shades of M. R. James.