"Entertain myself in studying it. Nothing may come of that, of course, but, like Emma, a mystery does appeal to me."
"So it does to me," agreed Grace. "Were it not for the fact that my intuition tells me that the map is going to play an important part in our journey, I should not have been in favor of making a copy of it, so take good care of the copy, Elfreda dear."
The rest of the evening was spent in discussing their mysterious find and all sorts of theories were advanced for the box being buried by the leaning cross. Hi Lang listened to all of this, but made no comment. He had his own ideas on the subject.
Next morning Hi was out long before the others were awake, making an investigation on his own account. He had barely begun this when, upon glancing up, he saw the solitary horseman far out on the desert, sitting motionless, apparently observing the camp of the Overland Riders.
The guide took his time at what he was doing, at the same time keeping a watchful eye on the distant horseman.
"I thought so!" exclaimed Hi Lang. "I think I'll give that fellow a run," he decided after a moment's reflection, during which he observed the watcher narrowly.
Catching up his pony, the guide quickly saddled, and, mounting, started across the desert at a brisk gallop. Five minutes later the solitary horseman turned his pony about and dashed away. Hi threw up his rifle and sent a bullet after the man, continuing to fire until the magazine of his rifle was emptied.
After reloading Hi thrust the rifle into its saddle boot and rode on until he reached the point from which the horseman had been observing. Hi Lang got down and again examined the hoof-prints of the watcher's pony.
"Huh!" he grunted. "That cayuse will keep on until something hits him—hits him hard. I reckon I begin to smell a mouse, and I think Mrs. Gray does, too. Hope she didn't hear me shooting back there. But none of that outfit is so sleepy or thick-headed that they don't see or hear pretty much everything that's going on about them."
Having freed his mind, Hi remounted and rode slowly back towards the camp. The Chinaman was getting breakfast when Mr. Lang rode in and tethered his pony.