Indeed it would have taken a monkey or a bird to climb the place which the beetle was now walking up. It was a smooth, flat part of the mountain’s side, steep as a wall. But presently, when the Jabizri was no more than ten feet above our heads, we all cried out together. For, even while we watched him, he had disappeared into the face of the rock like a raindrop soaking into sand. “He’s gone,” cried Polynesia. “There must be a hole up there.” And in a twinkling she had fluttered up the rock and was clinging to the face of it with her claws. “Yes,” she shouted down, “we’ve run him to earth at last. His hole is right here, behind a patch of lichen—big enough to get two fingers in.” “Ah,” cried the Doctor, “this great slab of rock then must have slid down from the summit and shut off the mouth of the cave like a door. Poor fellows! What a dreadful time they must have spent in there!—Oh, if we only had some picks and shovels now!” “Picks and shovels wouldn’t do much good,” said Polynesia. “Look at the size of the slab: a hundred feet high and as many broad. You would need an army for a week to make any impression on it.” “I wonder how thick it is,” said the Doctor; and he picked up a big stone and banged it with all his might against the face of the rock. It made a hollow booming sound, like a giant drum. We all stood still listening while the echo of it died slowly away. And then a cold shiver ran down my spine. For, from within the mountain, back came three answering knocks: _Boom!... Boom!... Boom!_ Wide-eyed we looked at one another as though the earth itself had spoken. And the solemn little silence that followed was broken by the Doctor. “Thank Heaven,” he said in a hushed reverent voice, “some of them at least are alive!” PART FIVE _THE FIRST CHAPTER_ A GREAT MOMENT THE next part of our problem was the hardest of all: how to roll aside, pull down or break open, that gigantic slab. As we gazed up at it towering above our heads, it looked indeed a hopeless task for our tiny strength. But the sounds of life from inside the mountain had put new heart in us. And in a moment we were all scrambling around trying to find any opening or crevice which would give us something to work on. Chee-Chee scaled up the sheer wall of the slab and examined the top of it where it leaned against the mountain’s side; I uprooted bushes and stripped off hanging creepers that might conceal a weak place; the Doctor got more leaves and composed new picture-letters for the Jabizri to take in if he should turn up again; whilst Polynesia carried up a handful of nuts and pushed them into the beetle’s hole, one by one, for the prisoners inside to eat. “Nuts are so nourishing,” she said. But Jip it was who, scratching at the foot of the slab like a good ratter, made the discovery which led to our final success.