The ringing sound he had heard only added to his bewilderment. It really was absurd to suspect the existence of a telephone circuit in the wilderness, nevertheless in his tour of the outer premises the corporal had looked for telephone wires. Had there been a line of any sort leading to the cabin, the snow-covered strands would have revealed themselves in the bright glare of his flashlight. He had found no wires.
The idea of a radio set occurred to him, and was immediately abandoned. Such a means of communication would require aerials and a connecting wire running to the cabin; or, if not that, at least an inside loop. Also there would have to be batteries, not to mention the bulky receiving and transmitting instruments. There was no such equipment on the premises; and an escaping fugitive could not have had time to dismantle and lug away a radio outfit. Of this he was positive: the voice he heard was not talking by wireless.
He checked up his facts, and considered the last remaining possibility—a chance so remote that it was scarcely worth thinking about. Could there be a tunnel or conduit leading underground to the cabin? He could conceive of no motive that would induce men to undertake the enormous labor of digging a trench through the forest. The notion was preposterous. But he had his report to write, and he was trained to thoroughness in all matters of investigation. It would be easy enough to determine if the ground had ever been broken.
Equipping himself with the spade he had used to pry up the floor boards, he proceeded to shovel a narrow pathway around the cabin, tossing aside the light covering of snow, and inspecting the bare soil underneath. He worked assiduously, and it did not take him a great while to complete the full circuit of the building. The ground was strewn naturally with the season's carpet of leaves and fallen twigs, and the topsoil below was the rich forest loam that requires ages in making. The experienced woodsman needed only a glance around the circular pathway to assure himself that the ground hereabouts had never been disturbed since the beginning of time. He was convinced finally, beyond all doubt. There was no tunnel.
Dexter tossed his shovel aside, and stood for a while by the open door of the cabin. His lips had fallen apart, and his head was thrown up to listen. But he heard only the familiar sounds of the forest, the moaning of the north wind in the trees, the crack and snap of sap-frozen branches. All else was silence. The eerie plaint of the owl came wavering from the darkness, but the empty, ghostly note seemed only a part of the great hush that brooded over the wilderness. The last man left on earth could not feel a sense of lonesomeness more poignant than Dexter felt at that moment, as he stood before the doorway of death, vainly waiting for some sound or movement to break the stillness about him. But for the discharged revolver in his pocket, and his knowledge of what lay in the two sleeping bunks, he might almost have persuaded himself that the events of the last two hours were the illusions of a strangely disordered brain.
He had investigated the cabin inside and outside, had left nothing undone that a searcher could possibly do. The mystery of it all seemed to lie beyond human power of solving. As he remained there, sentinel-like in the darkness, his hand strayed to his pocket and brought out a pipe and tobacco pouch. He carefully stuffed the bowl with fine cut leaf, and then absent-mindedly returned both pouch and pipe to his pocket. For a while longer he lingered by the doorway, his unseeing glance roving slowly about him. Then, with an ironic shrug, he suddenly stirred and stepped out into the clearing.
Inasmuch as he had seen everything there was to be seen about the cabin and its immediate premises, it occurred to him that he might as well extend his circle. The intuitive sense that belongs to all ramblers of the silent places seemed to tell him during the last few minutes that he was alone in the valley. The "feel," the woodsmen and mountaineers say, has nothing to do with the consciousness of smell or hearing or sight. Dexter merely felt that now there was no one else in the neighborhood. He did not expect to make any momentous discoveries, but a restive will demanded action of some sort. Flashing his light before him, he chose his direction at random and strode across the clearing.
At the edge of the open ground he found a runway that wild animals had trod out through the thicket during seasons past. He glanced among the trailing branches and checked himself abruptly, his eyes blankly staring. In the snow he saw the freshly made outline of a narrow, high-arched foot—a woman's shoeprint.