Years ago Peggy Sloane, only daughter of old Cornelius Sloane, familiarly known as the Professor, an antique dealer, met a millionaire art dealer named Stuart Watson and was prevailed by his hypnotic power to go through a marriage ceremony with him. A week passed and she returned, broken in spirit and body. Later, when her baby was born, she died. One night, while playing chess, old Sloane learns of the return to America of this man Watson and resolves to be revenged. Accordingly, it is arranged to have Watson come to the house of the old man. Watson, realizing that his perfidy is known, tries to subject Sloane to his hypnotic will but the latter, by his superior will-power, subjects Watson, bringing before his mind the vision of the girl he wronged. Coming out of the trance, Watson is told that every night at 11 o'clock the same vision will appear to him. It so transpires, and later, driven to despair by the awful apparition, he takes an overdose of drugs and dies. Thus the Professor feels his revenge is complete.