the garments to three dark Easterners who had apparently entered in the boat just ahead of the cutter.

The three dark Orientals, their faces gleaming with strange fanaticism, quickly donned the robes and hoods and passed hurriedly on down the tunnel. At once Campbell and Ennis stepped calmly up to the hooded custodians of the robes, and extended their hands.

One of the hooded figures took down two robes and handed them to them. But suddenly one of the other hooded men spoke sharply.

Instantly all the hooded men but the one who had spoken, with loud cries, threw themselves forward on Campbell and Paul Ennis.

Taken utterly by surprize, the two had no chance to draw their guns. They were smothered by gray-robed men, held helpless before they could move, a half-dozen pistols jammed into their bodies.

Stupefied by the sudden dashing of their hopes, the detective and the young American saw the hooded man who had spoken slowly lift the concealing gray cowl from his face. It was the dark, coldly contemptuous face of Chandra Dass.

4. The Cavern of the Door

Chandra Dass spoke, and his strong, vibrant voice held a scorn that was almost pitying.

"It occurred to me that your enterprise might enable you to escape the daggers of my followers, and that you might trail us here," he said. "That is why I waited here to see if you came.

"Search them," he told the other hooded figures. "Take anything that looks like a weapon from them."

Ennis stared, stupefied, as the gray-hooded men obeyed. He was unable to believe entirely in the abrupt reversal of all their hopes, of their desperate attempt.

The hooded men took their pistols from Ennis and Campbell, and even the small gold knife attached to the chain of the inspector's big, old-fashioned gold watch. Then they stepped back, the pistols of two of them leveled at the hearts of the captives.

Chandra Dass had watched impassively. Ennis, staring dazedly, noted that the Hindoo wore on his breast a different jewel-emblem from the others, a double star instead of a single one.

Ennis' dazed eyes lifted from the blazing badge to the Hindoo's dark face. "Where's Ruth?" he asked a little shrilly, and then his voice cracked and he cried, "You damned fiend, where's my wife?"

"Be comforted, Mr. Ennis," came Chandra Dass' chill voice. "You are going now to join your wife, and to share her fate. You two are going with her and the other sacrifices through the Door when it opens. It is not usual," he added in cold mockery, "for our sacrificial victims to walk directly into our hands. We ordinarily have a more difficult time securing them."

He made a gesture to the two hooded men with pistols, and they ranged themselves close behind Campbell and Ennis.

"We are going to the Cavern of the Door," said the Hindoo. "Inspector Campbell, I know and respect your resourcefulness. Be warned that your slightest attempt to escape means a bullet in your back. You two will march ahead of us," he said, and added mockingly, "Remember, while you live you can cling to the shadow of hope, but if these guns speak, it ends even that shadow."

Ennis and Inspector Campbell, keeping their hands elevated, started at the Hindoo's command down the softly lit rock tunnel. Chandra Dass and the two hooded men with pistols followed.

Ennis saw that the inspector's sagging face was expressionless, and knew that behind that colorless mask, Campbell's brain was racing in an attempt to find a method of escape. For himself, the young American had almost forgotten all else in his eagerness to reach his wife. Whatever happened to Ruth, whatever mysterious horror lay in wait for her and the other victims, he would be there beside her, sharing it!

The tunnel wound a little further downward, then straightened out and ran straight for a considerable length. In this straight section of the rock passage, Ennis and Campbell for the first time perceived that the walls of the tunnel bore crowding, deeply chiseled inscriptions. They had not time to read them in passing, but Ennis saw that they were in many different languages, and that some of the characters were wholly unfamiliar.

"God, some of those inscriptions are in Egyptian hieroglyphics!" muttered Inspector Campbell.

The cool voice of Chandra Dass said, behind them, "There are pre-Egyptian inscriptions on these walls, inspector, could you but recognize them, carven in languages that perished from the face of earth before Egypt was born. Yes, back through time, back through mediæval and Roman and Egyptian and pre-Egyptian ages, the Brotherhood of the Door has existed and has each year gathered in this place to open the Door and worship with sacrifices They Beyond it."

The fanatic note of unearthly devotion was in his voice now, and Ennis shuddered with a cold not of the tunnel.

As they proceeded, they heard a muffled, hoarse booming somewhere over their heads, a dull, rhythmic thunder that echoed along the long passageway. The walls of the tunnel now were damp and glistening in the sourceless soft light, tiny trickles running down them.

"You hear the ocean over us," came Chandra Dass' voice. "The Cavern of the Door lies several hundred yards out from shore, beneath the rock floor of the sea."

They passed the dark mouths of unlit tunnels branching ahead from this illuminated one. Then over the booming of the raging sea above them, there came to Ennis' ears the distant, swelling chant they had heard in the water-cavern above. But now it was louder, nearer. At the sound of it, Chandra Dass quickened their pace.

Suddenly Inspector Campbell stumbled on the slippery rock floor and went down in a heap. Instantly Chandra Dass and his two followers recoiled from them, the two pistols trained on the detective as he scrambled up.

"Do not do that again, inspector," warned the Hindoo in a deadly voice. "All tricks are useless now."

"I couldn't help slipping on this wet floor," complained Inspector Campbell.

"The next time you make a wrong step of any kind, a bullet will smash your spine," Chandra Dass told him. "Quick—march!"

The tunnel turned sharply, turned again. As they rounded the turns, Ennis saw with a sudden electric thrill of hope that Campbell held clutched in his hand, concealed by his sleeve, the heel-hilted knife from his shoe. He had drawn it when he stumbled.

Campbell edged a little closer to the young American as they were hastening onward, and whispered to him, a word at a time.

"Be—ready—to jump—them——"

"But they'll shoot, your first move——" whispered Ennis agonizedly.

Campbell did not answer. But Ennis sensed the detective's body tautening.

They came to another turn, the strong, swelling chant coming loud from ahead. They started around that turn.

Then Inspector Campbell acted. He whirled as though on a pivot, the heel-knife flashing toward the men behind them.

Shots coughed from the pistols that were pressed almost against his stomach. His body jerked as the bullets struck it, yet he remained erect, his knife stabbing with lightning rapidity.

One of the hooded men slumped down with a pierced throat, and as Campbell sprang at the other, Ennis desperately launched himself at Chandra Dass. He bore the Hindoo from his feet, but it was as though he was fighting a demon. Inside his gray robe, Chandra Dass writhed with fiendish strength.

Ennis could not hold him, the Hindoo's body seeming of spring-steel. He rolled over, dashed the young American to the floor, and leaped up, his dark face and great black eyes blazing.

Then, half-way erect, he suddenly crumpled, the fire in his eyes dulling, a call for help smothered on his lips. He fell on his face, and Ennis saw that the heel-knife was stuck in his back. Inspector Campbell jerked it out, and put it back into his shoe. And now Ennis, staggering up, saw that Campbell had knifed the two