The matter to Grenville seemed simple enough. The brink overhung the wall itself, in consequence of which the ladder swung quite free, down the face of the scarp, till it touched at a jutting ledge below. It swayed to and fro and sagged a bit loosely at some of the rungs, but it could not be broken by his weight. He made no attempt at a rapid descent, neither did he pause to enjoy the scenery. When the ledge was reached he rested, made certain no sharp-edged stone could impinge upon and perhaps cut into his twisted creepers, and again proceeded downward. His course for a matter of two or three fathoms was rendered rather more difficult by the fact the ladder lay closely bent against the wall, instead of hanging free. The rock face was pitted and exceedingly rough, its indentations ill-arranged for footholds and far too treacherous for any such employment. Grenville was nearly at the lower lip of this projection before he attempted a look below to determine what he was approaching. He discovered then it was undercut again--and likewise that his ladder was considerably short. Its lower end dangled about with irregular gyrations as he shifted his weight from rung to rung. It was fully two yards above the water. There was nothing in sight on which to plant his feet, so far as he could discern from the point then occupied. He continued down the ledge. When he reached its base, his suspicions were immediately confirmed. It overhung a cavern, which was not, however, the cave. To the final rung but one of his ladder he descended, and there he rested to have a look about. He was hanging directly before a massive pot-hole in the cliff--a huge, roughly rounded sort of chamber, the roof of which was arched. On the left, it shared its pitted wall with a second and smaller chamber. On the right, its edge was jaggedly broken against a yawning hole. This hole was undoubtedly the cave-mouth described by the documents found in the hidden tube. From this point only, as Grenville could see, would its mouth be readily discovered. Thick curtains of greenery, draped from its neighboring walls of rock, would shield it from view from passing boats, unless they should nose to its portals. This, with a swirling and dangerous tide, no craft would be likely to attempt. The shrubbery, hanging so thickly from the ledge, afforded Grenville a puzzle. He knew it could not be a seaweed, since the tide never rose to such a level. He presently realized it was simply an air plant of unusually luxuriant growth. Its roots had found lodgment in a crevice, where nothing would be likely to disturb it in its possession. Concerning the possible contents of the cave, its extent, or immediate surroundings, there was nothing to be discovered from his ladder, twist as he might or crane his neck to stare in the cavern's mouth.