To this Quarles pointed. "That is our way," he said. "We'll use what cover we can." We plunged into the wood again, and were soon in the wilderness, forcing our way, sometimes with considerable difficulty, through the undergrowth. Once or twice the professor gave me a warning gesture, but he did not speak. He had evidently some definite goal, and I was conscious of excitement as I followed him. For an hour or more he turned this way and that, exploring every little ravine he could discover, grunting his disappointment each time he failed to find what he was looking for. "I said I wasn't certain," he whispered when our path had led us into a damp hollow which looked as if it had not been visited by man for centuries. "My theory seems--and yet this is such a likely place. There must be a way." He was going forward again. The hollow was surrounded by perpendicular walls of sand and chalk; it was a pit, in fact, which Nature had filled with vegetation. The way we had come seemed the only way into it. "Ah! this looks promising," Quarles said suddenly. In a corner of the wall, or, to be more precise, filling up a rent in it, was a shed, roughly built, but with a door secured by a very business-like lock. "I think the shed is climbable," said Quarles. "Let's get on the roof. I am not so young as I was, so help me up." It was not much help he wanted. In a few moments we were on the roof. "As I thought," he said. "Do you see?" The shed, with its slanting roof, served to block a narrow, overgrown path between two precipitous chalk walls. "We'll go carefully," said Quarles. "There may be worse than poachers' traps here." Without help from me he dropped from the roof, and I followed him. The natural passage was winding, and about fifty yards long, and opened into another pit of some size. A pit I call it, but it was as much a cave as a pit, part of it running deeply into the earth, and only about a third of it being open to the sky. The cave part had a rough, sandy floor, and here was a long shed of peculiar construction. It was raised on piles, about eight feet high; the front part formed a kind of open veranda, the back part being closed in. The roof was thatched with bark and dried bracken, and against one end of the veranda was a notched tree trunk, serving as a ladder. "As I expected," said Quarles, with some excitement. "We must get onto the veranda for a moment. I think we are alone here, but keep your ears open." The shed was evidently used sometimes. There was a stone slab which had served as a fireplace, and from a beam above hung a short chain, on which a pot could easily be fixed. "We'll get away quickly," said Quarles. "Patience, Wigan. I believe we are going to witness a wonderful thing." "When?" "In about thirty hours' time."