The Mystery of Voodoo Manor (en Inglés) - Florence M. Pettee

An eccentric old woman, scornful of all superstition, fills a single locked chamber of her isolated manor with charms, hexes, and ill-omened curios from around the world. When she invites a renowned woman investigator to share her secret, she hints darkly that her own death may be near at hand.

That night, masked figures prowl the grounds. By dawn she is found stabbed inside the sealed room-the door locked from within, the window high above smooth, untouched earth. The murder weapon is one of her own cursed treasures: a slim foreign dagger set with a single opal eye.

To solve this seemingly impossible crime, the investigator must untangle a scheming niece, a hidden fortune in pearls, and a method of murder so audacious it seems almost supernatural. Was it human cunning-or had the old woman's mocked omens claimed her at last?