A wealthy industrialist's son has been kidnapped from the historic Burg Alnwick Hotel in the hills above Ellicott City. The man asks his trusted friend, Dr. R. L. McReady Knibbs, a well-known physician, psychiatrist, and investigator, to solve the crime without police involvement. A trio of local women is enlisted to aid Knibbs in finding the perpetrators before harm comes to the boy.Alice Gillhaney, a young woman troubled by visions of ghosts and other spirits, comes to the attention of Dr. Knibbs at the outset of the investigation.

The doctor had been planning to write a book on the relationship between psychosis and the occult, and is thus fascinated by Alice. As the investigation unfolds, it becomes apparent that Alice's ravings are not random, but have increasing relevance to the case before them.