This is one of the finest, most ingenious, and most atmospheric of the classic "locked room" mystery novels of John Dickson Carr. It is also one of his most somber and frightening books. While the author is most famous for his intricate and hard to solve murder puzzles, at least some of his hardcore fans like myself most enjoy the brooding atmosphere he creates, with a hint of the supernatural hanging over sometimes appalling crimes.
He Who Whispers is particularly great in its creation of this mysterious atmosphere. A man is brutally murdered under seemingly inexplicable circumstances, alone atop a remote tower. A female suspect is accused of being a soulless, bloodthirsty vampire, though to all appearances she is a modest and intelligent young woman. Oddly, as the novel wears on, this accusation seems at the same time absurd, and yet quite plausible! It is most cleverly handled, and resolved, by the author.
What really makes this book stand out among the author's many fine novels, is its uniquely, intensely romantic aspect. The point of view character (NOT the brilliant detective Gideon Fell, nor his stolid "Watson," Inspector Hadley) is drawn to two interesting, intelligent women, both of whom are potential suspects. One is a resourceful and determined investigative journalist, with, as it turns out, a rather murky connection to the case somewhere in her own past. The other is a lovely, sad governess who has apparently been wrongly accused of murder as well as other misdeeds....but how innocent is she really?
The mystery is ultimately sorted out--but then it really gets interesting! The resolution of the tangled romance plotline is moving and unexpected, and yet entirely logical, given the author's odd, seemingly incompatible combination of anachronistic chivalry toward women and respect for independent, uninhibited females. If this sounds a bit vague that is because I am trying not to give away any plot details, as I would never forgive myself if I spoiled the suprises of a great Carr mystery novel like this one!