'We're trapped!' cried Sturt. 'A mass of the rock has settled here and blocked the tunnel.'
'It can't be completely blocked!' Campbell exclaimed. 'See, the tide still runs out beneath it. Our one chance is to swim out under the blocking mass of rock, before the whole cliff gives way!'
'But there's no telling how far the block may extend——' Sturt cried.
Then as Campbell and Ennis stripped off their coats and shoes, he followed their example. The rumble of grinding rock around them was now continuous and nerve-shattering.
Campbell helped Ennis lower Ruth's unconscious form into the water.
'Keep your hand over her nose and mouth!' cried the inspector. 'Come on, now!'
Sturt went first, his face pale in the searchlight beam as he dived under the rock mass. The tidal current carried him out of sight in a moment.
Then, holding the girl between them, and with Ennis' hand covering her mouth and nostrils, the other two dived. Down through the cold waters they shot, and then the swift current was carrying them forward like a mill- race, their bodies bumping and scraping against the rock mass overhead.
Ennis' lungs began to burn, his brain to reel, as they rushed on in the waters, still holding the girl tightly. They struck solid rock, a wall across their way. The current sucked them downward, to a small opening at the bottom. They wedged in it, struggled fiercely, then tore through it. They rose on the other side of it into pure air. They were in the darkness, floating in the tunnel beyond the block, the current carrying them swiftly onward.
The walls were shaking and roaring frightfully about them as they were borne round the turns of the tunnel. Then they saw ahead of them a circle of dim light, pricked with white stars.
The current bore them out into that starlight, into the open sea. Before them in the water floated Sturt, and they swam with him out from the shaking, grinding cliffs.
The girl stirred a little in Ennis' grasp, and he saw in the starlight that her face was no longer dazed.
'Paul——' she muttered, clinging close to Ennis in the water.
'She's coming back to consciousness—the water must have revived her from that drug!' he cried.
But he was cut short by Campbell's cry. 'Look! Look!' cried the inspector, pointing back at the black cliffs.
In the starlight the whole cliff was collapsing, with a prolonged, terrible roar as of grinding planets, its face breaking and buckling. The waters around them boiled furiously, whirling them this way and that.
Then the waters quieted. They found they had been flung near a sandy spit beyond the shattered cliffs, and they swam toward it.
'The whole underground honeycomb of caverns and tunnels gave way and the sea poured in!' Campbell cried. 'The Door, and the Brotherhood of the Door, are ended for ever!'
