John Holdsworth, former rare book dealer, is a haunted man. Having lost first his child, then his wife, in separate drowning accidents, his business has also gone under. Mrs. Holdsworth, before her apparent suicide, was obsessed with the idea that her son's spirit was communing with her, and when she dies, Holdsworth writes a monograph, The Anatomy of Ghosts, debunking their existence. John is floundering pretty badly when an unexpected offer of employment comes his way. Lady Anne Oldershaw, who has read his monograph, wishes to engage his services for two purposes, to organize her late husband's library, and to save her son Frank, a Cambridge undergrad, from apparent madness - he is convinced he's seen a ghost, and is currently housed in an asylum for the insane.