Sir Lionel was out of the game, and with him the Kirghiz hunters. Gray was alone for the first time since his visit to Van Schaick the evening that he had contracted to find the Wusun. He smiled grimly as he thought how matters had changed. Here he was at the gate of the Wusun, the captive race. But Sir Lionel had found them hardly what Gray expected. A leper's colony is not a pleasant thing to visit. And this one was unusually well guarded. Behind these guards, in the ruins of Sungan, was Mary Hastings. This thought had gnawed at the American's heart for the past twelve hours. The girl he loved--he could no more conceal that fact from himself than he could lose sight of the Gobi--was among the lepers. Was she alive? He did not know. The guards of Sungan did not seem overmerciful. But why should they kill her? No, he reasoned, she was alive. She must be alive. And she was waiting for help to come. She might have discovered that her uncle had escaped in the fight before the ruins. And she knew that Gray was coming to Sungan in their tracks. What Gray was going to do after he found the girl, he did not know. He had long ago discovered that a multitude of difficulties confuse and baffle a man. He had trained himself to tackle only one thing at a time; not only that, but to think of only one thing. If he found Mary, there would be time to consider what would come next. The thought of the girl urged him on, so that it was hard to keep an even pace. But he was aware of the uselessness of blind haste. He struck a steady gait which he could keep up for hours, a swift walk that left the dunes behind rapidly. These dunes, he noticed, were not as high as at first. The desert was becoming more level, the soil harder. At some points the clay surface appeared between the sand ridges. Gray did not try to eat. Nor did he drink, knowing the folly of that at the beginning of a march. In time he would do both, not now. The man's powerful frame enabled him to keep up the pace he had set without fatigue or loss of breath. This was the secret of Gray's success as an explorer--his careful husbanding of his great vitality, and his refusal to worry over problems that lay in the future. When the vision of Mary flashed on him as he watched the summits of the dunes, silvered by the cold moonlight, he put it aside resolutely. The last sight of the girl--the slender figure perched jauntily on the camel as she rode away after their quarrel--tormented him from time to time. In spite of himself an elfin chord of memory visioned the friendly gray eyes, and the delicate face of Mary Hastings. Gray set himself to considering his situation, realizing that he had desperate need of all his wits if he was to face Sungan and its people. First there was the puzzle of the camel tracks that had frightened Mirai Khan. These tracks had been left by the party that had attacked Sir Lionel and himself. They had been sighted the day before.