The nerves of that trio of watchers so close by quivered with excitement. As their lookout was bathed in deep shadow there was no possibility of their being seen by the intruder, even though he looked directly that way, if only the boys made no movement. Satisfied at length after several trials that he had struck the exact location for which he searched, the man, still bending down, started to push the spade into the turf. It was soft and pliable so near the house, where the shade of the foliage above prevented the sun from baking the surface. Consequently, the dwarf seemed to be having no great difficulty in digging. He worked in utmost silence. Not once did Frank catch the slightest sound, as of the spade striking a root or a possible stone. Indeed, in a way it was uncanny. Lanky, being gifted with a lively imagination, could easily picture the queer little man as a ghostly grave-digger, plying his trade at this hour approaching midnight. It was useless trying to guess what object the fellow had in view, for the boys had not the remotest clue to guide them. But by exercising patience they were likely to find the solution of the mystery when he "struck oil." His caution still clung to him, it seemed, and he took nothing for granted. As systematically as clock-work that bushy head would be raised and turned around in every direction. Then, as if convinced he had nothing to fear, the digger would once more get down to work and deepen the hole he had already made. Apparently, whatever he was after must be buried at some considerable depth below the surface. Already he had quite a good-sized pile of loam heaped up. Then, all of a sudden, he seemed to take the alarm, for the boys saw him flatten out until he "looked like a flapjack on the ground." At the same moment a distant sound, as of the regular beat of a pony's hoofs, was faintly borne to the ears of the watching boys. They all understood what it meant, knowing that Buster Lightfoot had been missing at supper and was believed to be far off on the range looking up strays. He was now returning on a tired pony, and doubtless himself as hungry as a wolf. Yes, now the boys knew he was turning Buckskin into the corral, after which they could see him heading for the bunk-house, his burly frame looming up in the slanting rays of the failing moon. Buster knew better than to make any undue racket when returning at so late an hour, for he would have had the rest of the boys about his ears like a swarm of angry bees. He would find plenty of food laid aside for him by the experienced Charlie Gin Sing, and after disposing of the bread and meat and the hot coffee contained in an enormous thermos jug, he was expected to turn in for the rest he so sadly needed.