Gray thought of the tale Delabar had mentioned--of the sand that came down on the city of the Gobi, as retribution for some sin against the religions of Asia. Also, Mirai Khan had said no city was to be seen. And Brent had claimed to see some isolated towers. "These towers," he started to explain what was in his mind. "Are the summits of the palaces of Sungan, sir. In them I shall find the white race of Asia, the captive people of the Wusun." "But, Uncle," protested the girl, "the stone was erected four hundred years ago. If the Chinese had wanted to, they might have killed off the remaining Wusun since that time." "The ancient Chinese annals," observed Sir Lionel tolerantly, "state that the Wusun, the 'Tall Ones,' were formidable fighters. The Sacae or Scythians from whom they are descended were one of the conquering races of the world. It is this heritage of strength which has preserved the remnant of the Wusun--for us to find." Gray faced the Englishman across the table. Sir Lionel had changed to a neat suit of clean duck for the meal. Mary was fastidiously dressed in white, a light shawl over her slender shoulders. He felt keenly his own untidy attire. Moreover, the girl seemed bent on making fun of him. "Captain Gray is a hunter, you know, Uncle," she remarked, glancing coolly at the uncomfortable American. "Really, your talk about the Wusun must bore him. He has come to shoot antelope. Or is it wild camels, Captain Gray?" Gray met her glance steadily. He saw that she was heart and soul with Sir Lionel in the latter's quest, and guessed that his own confession must terminate any possibility of friendship between them. "Neither," he said gravely. "I have meant to tell you before this. But at first I was so surprised at finding----" "That we guarded our ponies, Captain Gray?" The girl's eyes twinkled and she bit her lip. "A white woman instead of a Chinaman--I didn't confess, as I should have done." "But Mirai Khan confessed." Gray flushed. "I was sent to the desert, Sir Lionel, to find the Wusun. I am employed by the American Exploration Society. And I am going to do my best to get to Sungan--ahead of you, if possible." The effect of his words was curious. The girl studied him silently. Sir Lionel stroked his blond mustache, plainly ill at ease. Neither seemed surprised. "So you see," Gray made the statement as blunt as possible, "I am your rival. I meant to tell you before. Naturally, it is my duty to use the information you have given me. But I want to make my position clear before we go any further." Sir Lionel's first words were not what Gray expected. "You are not a scientist, sir?" "I am not. Professor Delabar, who was to have come with me, was forced to turn back at Liangchowfu." "Then you are alone? Without a caravan?"