Swiftly and silently, “X” moved down the dark corridor, stopping occasionally to listen to the whisper of footsteps ahead of him. Suddenly, a tiny spot of light shone on what appeared to be a blank wall in front of him. He saw the hand of the Ghoul holding a flashlight and turning the key in the lock of a door. The door opened and closed behind the Ghoul before “X” had a chance to follow. As he approached on tiptoe, a faint hissing sound came out of the darkness. It was a steady hiss like the escape of—
And in another moment, he knew it was gas — poisonous chlorine. He could feel its sting in his eyes and smell its acrid odor. “X” knew that the Ghoul, believing that “X” had in some way managed to inform the police of the gang’s headquarters, was deserting his men and burning his bridges behind him. This was his own secret exit, and the quantities of poison gas hissing into the passage had been prepared for just such an emergency.
AGENT “X” held his breath and closed his eyes against the poisonous, stinging vapor. The fingers of his right hand groped across the panel, searching the keyhole. His right hand fingered the bunch of master keys in his pocket. Without a light, it was impossible for him to pick out the exact key that would unlock the door. Finding the keyhole, he tried them one at a time. His lungs were aching; his heart throbbing at his temples. Yet to breathe was to die. At last he found a key that scraped through the eye of the lock. Just as he turned the key, a dull boom sounded hollowly throughout the cellars.
“X” threw open the door and stepped into a lighted room. Evidently this part of the catacombs was on a different lighting circuit than the other part. A ghostly wisp of yellow-green gas followed him into the room. He wanted to cough but dared not. He stepped into the next room. It appeared empty until “X” saw, beneath the yellow silk curtains that draped a doorway, the shoes and trousered legs of a man. Cautiously, he approached. He lifted the yellow curtains. The face of the man on the floor was covered with a yellow silk veil.
Revolver in hand, “X” knelt beside the still form. With the tips of his fingers, he lifted the yellow veil. Beneath was the chubby, red face of unconscious Mayor Grauman.
“Neatly trapped, Agent ‘X’,” came the Ghoul’s cold whisper.
“X” looked up quickly. Standing directly in front of a screen of Oriental design, was the Ghoul — the Ghoul without his silk mask, with only the hideous death-mask of Ah-Fang covering his real features. The automatic held in his unflinching fingers was directed at the Agent’s heart.
“I knew,” the Ghoul whispered, “that curiosity concerning my identity would prompt you to took beneath the veil that covered the mayor’s face. That is why I placed him there as a decoy when I heard you had managed to gain entrance here in spite of my poison gas. In fact, now that the game is over, I think you must admit that I have outplayed you in every hand.”
“True,” the Secret Agent admitted. “Much as I hate to spoil your good opinion of yourself, I can’t resist telling you that I’ve known your identity for several hours. I was sure of my deduction when, in the guise of Morgan, I fell into your hands in the laboratory. Though your voice came from a reproducer in the ceiling, you were there in person with Vardson and the others. In fact, I might go so far as to say you took an active part in most of the crimes.
“In the laboratory, you were one of those living-dead men ranged along the wall. It is not difficult to fake the Amber Death when you have stained your skin the proper hue. A little lapel-button microphone enabled you to speak through the reproducer in the ceiling, though you were actually in the room. When I attacked your men, you took advantage of the confusion, stepped from the wall and dropped the yellow veil over your face.
“Your actual presence spurred the men to action, just as it did tonight at the mayor’s place. Phonograph records of your voice were used for all the Ghoul radio warnings in order that you might be busy elsewhere — busy shifting suspicion from your own shoulders, busy planning new murders in the very presence of the men you intended to murder.”
A chuckle sounded behind the Ghoul’s mask of mummified flesh. “No one will ever know the truth. Yu’an and Vardson alone knew my true identity. Vardson is beyond sane speech. You say that your knife found Yu’an’s throat. Not five minutes ago, I pressed an igniter that fired a charge which will result in the destruction of both laboratories and the Amber Death victims. The formula for the Amber Death will be destroyed. Only Vardson knew it. I have over a million dollars in cash and securities — the reward of my efforts. I have only to step through the rear door of this room, climb steps, and enter a garage where my car is waiting.”
Carried away with praise of himself, the Ghoul did not notice that “X” had shifted his empty revolver into the palm of his hand. With a sudden movement, he flung the weapon at the Ghoul’s head. The Ghoul ducked to one side, fired a shot that took “X” in the chest. But again the bullet-proof vest saved him. As he leaped, hands extended for the killer’s throat, the Ghoul fired again — this time, at the Agent’s head.
“X” ducked too late to avoid the shot entirely. It grazed the side of his head, dashed blinking red and yellow lights before his eyes, sent blood trickling into his eyes to blind him. Yet he had reached the Ghoul’s gun-hand and clung to it desperately, keeping the automatic turned away from himself.
For a moment, they were locked together, the Ghoul striving to break away from the Agent’s hold, and “X” battling to save himself from oblivion. With an unexpected twist of the wrist, “X” disarmed the Ghoul. The automatic clattered to the floor. But in making that desperate attempt, “X” had thrown himself slightly off balance. The Ghoul lunged forward, throwing “X” to the ground.
The shock of the fall seemed to clear “X’s” vision. He seized the Ghoul’s throat in his right hand. His left came up instinctively to lock over the Ghoul’s wrist. For in the Ghoul’s hand was something sharp and shiny. Not a knife, but a large hypodermic needle.
“The Amber Death,” the Ghoul gasped out. “One more charge of the Amber Death…. All yours.” And slowly but surely his hand bent forward, the needle seeking the flesh of the Agent’s wrist.
Suddenly, “X’s” knees came up, lifting his assailant. Then he straightened, all the strength of his body behind a kick that sent the Ghoul’s heels over head across the room. “X” was up in a second. His right hand swept up the Ghoul’s automatic from the floor. The Ghoul, completely winded by his fall, attempted to get up, couldn’t, and fell back to the floor.
Covering the man with the automatic, “X” seized him by the collar, picked him up, and threw him into a chair. As he did so, he noticed that the chair was one of those peculiar metal chairs similar to the one in which he had sat in China Bobby’s office. He saw that a covered cable led from the chair to a generator at the side of the room. Evidently, the Ghoul had used this contraption to torture the truth out of some one. It was a very good idea, the Agent decided.
“X” sprang to the generator and threw over the starting switch. The hum of the generator was drowned out by a shriek of pain and terror from the Ghoul. “X” cut the current slightly. For a moment, he watched the Ghoul writhing in an effort to drag himself from the chair. Then he said softly:
“Let me know when you are ready to sign a full confession. For every moment you delay, I shall step up the current another notch!”