"Two hours later Antonio discovered upon the stairs leading up to the drawing-room a curious little gold and enamel charm in the form of a child's old-fashioned wooden doll--a beautifully-made little thing," he went on; "and half an hour later a maid, while cleaning the boudoir outside the locked door giving entrance to the laboratory, was surprised to find a small spot of blood upon the white goat-skin mat. This seems to have aroused Antonio's apprehensions. A telegram to the Professor at the North British Hotel in Edinburgh, sent by his daughter, brought, about three o'clock in the afternoon, a reply stating that he was quite well, and it was not until seven o'clock last evening that Ethelwynn communicated with me, her father having suggested this in the note she had received. I called upon her at once, and was shown the note, the little golden doll, and the ugly stain upon the mat. By then my curiosity became aroused. I went out to a telephone at a neighbouring public-house, and, unknown to anybody, got on to the reception clerk at the North British Hotel in Edinburgh. In answer to my inquiry, the young lady said that during the day a telegram had arrived addressed to Professor Greer, and it had been placed upon the board where telegrams were exhibited. Somebody had claimed it, but no one of the name was staying in the hotel." "You have now said that the Professor was your friend," I remarked. "I understood you to say that he was an enemy." "I'll explain that later," said my companion impatiently, drawing hard at his pipe. "Let me continue to describe the situation. Well, on hearing this from Edinburgh, I drove to King's Cross, and, somewhat to my surprise, found that Professor Greer had left London by the train he had intended. The sleeping-car attendant who had travelled with him up North was just back, and he minutely described his passenger, referring to the fact that he refused to have an early cup of tea, because tea had been forbidden by his doctor." "A perplexing situation," I said. "How did you account for the bloodstain? Had any of the servants met with an accident?" "No, none. Neither dog, nor cat, nor any other pet was kept, therefore the stain upon the mat was unaccountable. It was that fact which caused me, greatly against Miss Ethelwynn's consent, to seek a locksmith and take down the two locked doors of the laboratory." And he paused, gazing once more straight into the flames, with a curious expression in those deep-set brown eyes. "And what did you find?" I eagerly inquired.