"But Mary!" groaned Donald Morris in agony, as the two men, their unsuccessful investigation over, stood for a moment in the vast loneliness of the great station. "I don't mind so much that we've lost all trace of her sister. It's Mary, Mary that I'm thinking about. Where has she gone? What has happened to her?" The fearful tension of the morning was apparent in every line of his weary white face. "Let Anne go! She's nothing to me! But find Mary, Clancy! Find Mary! Put every ounce of strength you have, every resource of your organization on it. Spend any amount of money. Leave no stone unturned. I'm afraid--I'm horribly afraid. She's----" Clancy put a restraining hand on his arm, and even while he spoke he was wondering if the same sinister idea which was creeping into his own thoughts had already, by any possibility, found a place in Morris's less experienced mind. It was hardly probable, Peter comforted himself with the thought. A thing so far outside the experience of the young sculptor would scarcely suggest itself. And if it did, it would be necessary to combat it as long as possible, for in that direction, Peter was sure, would lie madness for Donald Morris. "We'll get on the job at once, Mr. Morris," he said, promptly, reassuringly. "We'll search the city over to find any trace of her. She didn't leave the apartment with her sister. We know that much, anyway. If she took another cab----" "She's almost certain to have done that," Donald interrupted, eagerly. "She hated to walk through the streets, even for a short distance, and all the railroad stations are a long way from Waverly Place." "Well, if she took a cab, we'll find it," declared Peter, confidently. "But it may take a little time. I'll have to go to the office now, and get things started. You can't be any help about this part, and I'd advise you to get a rest. You aren't used to this kind of thing, and it's bound to knock you up. Go home and take it easy. I'll 'phone you if there's any news or if there's anything you can do. Let's get a cab, and I can drop you at your house on my way to the office. There are a few things I'd like to have you tell me, and that way we won't waste any time. How about it?" "All right," answered Morris, wearily. "But I wish you'd let me go with you. Somehow I feel----" "Yes, I guess I know how you feel, all right," said Peter, "but it won't be any good. You can't help, and you need to get quieted down. Come on." With sympathetic consideration he led Donald to a cab, selecting one which had the front windows closed, so that they might talk in privacy. As they turned into Seventh Avenue he said: "Now tell me everything you know about Miss Blake and her sister. Every little thing. You can never tell what might come in useful. How long have you known them?"