"Vanity. I was introduced to her one night at an Artists' Ball--the Albert Hall affair, you know--and I told her she had the figure of a Venus. I was consciously playing on her vanity for a purpose. In the thing I have done for the Agricultural Institute there is a recumbent figure, and I wanted the perfect model for it. The right woman is more difficult to get than you would imagine. Of course she agreed with me as to the perfectness of her figure, and then I began to doubt it. That settled the business. She fell into my trap and agreed to be the model." "Posing in the nude?" I asked. "Oh, that did not trouble her at all," answered Forbes. "I shouldn't be surprised if she had been a model in Paris studios before she blossomed out as a dancer. She spoke Russian, but I am inclined to think France had the honor of giving her birth. In return for her complaisance I promised to do a portrait bust of her for herself. That is it. If she is alive and comes to claim it I shall have to do her another one." "She was evidently a very beautiful woman," said Quarles, glancing in the direction of the bust. "Beautiful and bad, I fancy. Curiously enough, I did not hear of her disappearance until I telephoned to her flat two days after it had happened. She had broken an appointment to give me a final sitting, and I wanted to know why she hadn't come." "Was the final sitting for the Agricultural group?" Quarles asked. "No; for the bust there. I had to leave it as it was, but there is something in the line of the mouth which does not please me. What has become of her, do you suppose?" "Possibly some one or something she is afraid of has caused her to go into hiding," said Quarles. "Afraid! I doubt if she had any fear of devil or man. Have you seen Musgrave's portrait of her?" The professor nodded, and I thought it was curious that the Academy picture should be referred to so persistently. "She was like that," said Forbes. "Musgrave's is a wonderful piece of work." Involuntarily I glanced at the bust, and he noticed my surprise. "Oh, she was like that too at times," he said. "I should doubt if Musgrave ever saw her as you have represented her," said Quarles. "Perhaps not. He claims to paint character; possibly I might succeed in chiseling character, but give me a beautiful model, and as a rule I am content to show the surface only. Besides, the bust was for her, and I made the best of my subject." "And in the Agricultural piece?" asked Quarles. "Naturally I idealized her." "I suppose he is not the born artist that Musgrave is?" I said, when Forbes had left us. "I don't know," returned Quarles. "We will go and have another look at the bust, and I think on the way home we might drop in and have another look at Musgrave's picture." "That portrait bothers me," I said. "One might suppose it was the key to the mystery." "I am not sure that it isn't," Quarles answered.