“Where leads the Door?” rolled the chief priest’s voice.

Back up to him came the reply of hundreds of voices, muffled by the hoods but loud, echoing to the roof of the cavern in a thunderous response.

“It leads outside our world!”

The chief priest waited until the echoes died before his deep voice rolled on in the ritual.

“Who taught our forefathers to open the Door?”

Ennis, edging desperately closer and closer to the line of victims, felt the mighty response reverberate about him.

“They Beyond the Door taught them!”

Now Ennis was apart from the other priests on the dais, within a few yards of the captives, of the small figure of Ruth.

“To whom do we bring these sacrifices?”

As the high priest uttered the words, and before the booming answer came, a hand grasped Ennis and pulled him back from the line of victims. He spun round to find that it was one of the other priests who had jerked him back.

“We bring them to Those Beyond the Door!”

As the colossal response thundered, the priest who had jerked Ennis back whispered urgently to him. “You go too close to the victims, Chandra Dass! Do you wish to be taken with them?”

The fellow had a tight grip on Ennis’ arm. Desperate, tensed, Ennis heard the chief priest roll forth the last of the ritual.

“Shall the Door be opened that They may take the sacrifices?”

Stunning, mighty, a tremendous shout that mingled in it worshipping awe and superhuman dread, the answer crashed back.

"Let the Door be opened!"

The chief priest turned and his up-flung arms whirled in a signal. Ennis, tensing to spring toward Ruth, saw the two priests at the gray mechanism swiftly turn the knurled black knobs. Then Ennis, like all else in the vast cavern, was held frozen and spellbound by what followed.

The spherical web of wires pulsed up madly with shining force. And up at the center of the gleaming black oval facet on the wall, there appeared a spark of unearthly green light. It blossomed outward, expanded, an awful viridescent flower blooming quickly outward farther and farther. And as it expanded, Ennis saw that he could look through that green light! He looked through into another universe, a universe lying infinitely far across alien dimensions from our own, yet one that could be reached through this door between dimensions. It was a green universe, flooded with an awful green light that was somehow more akin to darkness than to light, a throbbing, baleful luminescence.

Ennis saw dimly through green-lit spaces a city in the near distance, an unholy city of emerald hue whose unsymmetrical, twisted towers and minarets aspired into heavens of hellish viridity. The towers of that city swayed to and fro and writhed in the air. And Ennis saw that here and there in the soft green substance of that restless city were circles of lurid light that were like yellow eyes.

In ghastly, soul-shaking apprehension of the utterly alien, Ennis knew that the yellow circles were eyes that that hell-spawned city of another universe was living that its unfamiliar life was single yet multiple, that its lurid eyes looked now through the Door!

Out from the insane living metropolis glided pseudopods of its green substance, glided toward the Door. Ennis saw that in the end of each pseudopod was one of the lurid eyes. He saw those eyed pseudopods come questing through the Door, onto the dais.

The yellow eyes of light seemed fixed on the row of stiff victims, and the pseudopods glided toward them. Through the open door was beating wave on wave of unfamiliar, tingling forces that Ennis felt even through the protective robe.

The hooded multitude bent in awe as the green pseudopods glided toward the victims faster, with avid eagerness. Ennis saw them reaching for the prisoners, for Ruth, and he made a tremendous mental effort to break the spell that froze him. In that moment pistol-shots crashed across the cavern and a stream of bullets smashed the pulsing web of wires!

The Door began instantly to close. Darkness crept back around the edges of the mighty oval. As though alarmed, the lurid-eyed pseudopods of that hell-city recoiled from the victims, back through the dwindling Door. And as the Door dwindled, the light in the cavern was failing.

“Ruth!” yelled Ennis madly, and sprang forward and grasped her, his pistol leaping into his other hand.

“Ennis quick!” shouted Campbell’s voice across the cavern.

The Door dwindled away altogether; the great oval facet was completely black. The light was fast dying too.

The chief priest sprang madly toward Ennis, and as he did so, the hooded hordes of the Brotherhood recovered from their paralysis of horror and surged madly toward the dais.

“The Door is closed! Death to the blasphemers!” cried the chief priest as he plunged forward.

“Death to the blasphemers!” shrieked the crazed horde below.

Ennis’ pistol roared and the chief priest went down. The light in the cavern died completely at that moment.

In the dark a torrent of bodies catapulted against Ennis, screaming vengeance. He struck out with his pistol-barrel in the mad melee, holding Ruth’s stiff form close with his other hand. He heard the other drugged, helpless victims crushed down and trampled under foot by the surging horde of vengeance-mad members.

Clinging to the girl, Ennis fought like a madman through a darkness in which none could distinguish friend or foe, toward the door at the side from which Campbell had fired. He smashed down the pistol-barrel on all before him, as hands sought to grab him in the dark. He knew sickeningly that he was lost in the combat, with no sense of the direction of the door.

Then a voice roared loud across the wild din, “Ennis, this way! This way, Ennis!” yelled Inspector Campbell, again and again.

Ennis plunged through the whirl of unseen bodies in the direction of the detective’s shouting voice. He smashed through, half dragging and half carrying the girl, until Campbell’s voice was close ahead in the dark. He fumbled at the rock wall, found the door opening, and then Campbell’s hands grasped him to pull him inside.

Hands grabbed him from behind, striving to tear Ruth from him, to jerk him back. Voices shrieked for help.

Campbell’s pistol blazed in the dark and the hands released their grip. Ennis stumbled with the girl through the door into a dark tunnel. He heard Campbell slam a door shut, and heard a bar fall with a clang.

“Quick, for God’s sake!” panted Campbell in the dark. “They’ll follow us we’ve got to get up through the tunnels to the water-cavern!”

They raced along the pitch-dark tunnel, Campbell now carrying the girl, Ennis reeling drunkenly along.

They heard a mounting roar behind them, and as they burst into the main tunnel, no longer lighted but dark like the others, they looked back and saw a flickering of light coming up the passage.

“They’re after us and they’ve got lights!” Campbell cried. “Hurry!”

It was nightmare, this mad flight on stumbling feet up through the dark tunnels where they could hear the sea booming close overhead, and could hear the wild pursuit behind.

Their feet slipped on the damp floor and they crashed into the walls of the tunnel at the turns. The pursuit was closer behind as they started climbing the last passages to the water-cavern, the torchlight behind showed them to their pursuers and wild yells came to their ears.

They had before them only the last ascent to the water-cavern when Ennis stumbled and went down. He swayed up a little, yelled to Campbell. “Go on get Ruth out! I’ll try to hold them back a moment!”

“No!” rasped Campbell. “There’s another way one that may mean the end for us too, but our only chance!”

The inspector thrust his hand into his pocket, snatched out his big, old-fashioned gold watch.

He tore it from its chain, turned the stem of it twice around. Then he hurled it back down the tunnel with all his force.

“Quick out of the tunnels now or we’ll die right here!” he yelled.

They lunged forward, Campbell dragging both the girl and the exhausted Ennis, and emerged a moment later into the great water-cavern. It was now lit only by the searchlight of their waiting cutter.

As they emerged into the cavern, they were thrown flat on the rock ledge by a violent movement of it under them. An awful detonation and thunderous crashing of falling rock smote their ears.

Following that first tremendous crash, giant rumbling of collapsing rock shook the water-cavern.

“To the cutter!” Campbell cried. “That watch of mine was filled with the most concentrated high-explosive known, and it’s blown up the tunnels. Now it’s touched off more collapses and all these caverns and passages will fall in on us at any moment!”

The awful rumbling and crashing of collapsing rock masses was deafening in their ears as they lurched toward the cutter. Great chunks of rock were falling from the cavern roof into the water.

Sturt, white-faced but asking no questions, had the motor of the cutter running, and helped them pull the unconscious girl aboard.

“Out of the tunnel at once!” Campbell ordered. “Full speed!”

They roared down the water-tunnel at crazy velocity, the searchlight beam stabbing ahead. The tide had reached flood and turned, increasing the speed with which they dashed through the tunnel.

Masses of rock fell with loud splashes behind them, and all around them was still the ominous grinding of mighty weights of rock. The walls of the tunnel quivered repeatedly.

Sturt suddenly reversed the propellers, but in spite of his action the cutter smashed a moment later into a solid rock wall. It was a mass of rock forming an unbroken barrier across the water-tunnel, extending beneath the surface of the water.

“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!”