“X” heard the window grate again. He swung the gun toward it, started to pump the trigger, but held his fire. His quick mind was already checking over impressions. Something had clicked in his memory.
THE window slammed back as a man leaped out. A shoe scraped against stone in the darkness outside, no blacker than that in the room. But in another moment, as “X” picked his way gingerly over the floor, nursing his bruised arm, lightness began to come. Not through the window, but from the bulbs overhead. The darkness was lifting again, as mysteriously as it had fallen — and it lifted on a room of death.
For Vivian de Graf lay sprawled on the rug by the overturned table. Crimson was spread over her blue pajama coat; crimson, just under the heart, darkening the glisten of the silken fabric.
The Agent crossed to her in one swift stride. He bent down and pressed his fingers on her outflung wrist. But there was no pulse flutter. That single shot, fired in the dark, had done its work well. Vivian de Graf was dead. Even so, she was beautiful, red lips a splash of color across the whiteness of her face, eyes closed as if in sleep.
But the Agent did not pause to stare. Hers was not the only beauty that had been stricken in that room. The frenzied slayer’s passion had not stopped at taking human life. Among the splintered pieces of pottery lay the stems and petals of a score of saffron orchids. The Agent’s eyes darted along the floor. Three vases filled with the flowers had been smashed. The spotted blossoms had been trampled on, their destruction as deliberate as the woman’s death, and done in the same murderous fury.
A single orchid, kicked accidentally under a chair, had escaped. The Agent picked it up, stared curiously. The poisonously spotted petals curled like living things. The flower’s dark center seemed an accusing eye.
He took an envelope from his pocket, dropped the flower in and slipped it in his coat. Then he glanced at the woman again, and noticed for the first time that the rug at her feet had been kicked away by her silken leg as she fell. Under the rug’s edge, close to the table, was a small metallic plate set just above the level of the floor. Some sort of electric switch — and the Agent’s eyes narrowed instantly.
He strode to it, placed his foot on the thing tentatively, and pressed down. Almost at once the lights above his head grew dimmer, and there was that strange buzzing in his ears. He took his foot off and the sensation stopped. He understood now. This was how the darkness had been made.
There was a hidden mechanism to produce it somewhere in the room. Wires led from it to this floor switch. Vivian de Graf had tricked him when she pretended to reach for the phone. She had stepped on the switch beneath the rug, started the mechanism in motion. The shot that found her heart and made her fall, had released her weight from the plate and automatically turned the mechanism off.
Agent “X” began a hurried search for the thing that could bring darkness blacker than night to human eyes. It would be hidden, but it must be somewhere in this chamber. He bent above the floor switch again, intent on seeing which way the wires beneath it led.
But abruptly his search ceased. For a car whined in the night outside and came to a purring halt. Then voices muttered and footsteps sounded close to the vestibule door. The bell of Vivian de Graf’s apartment made a silver tinkle in the kitchenette, a moment passed, and a key grated in the lock.
The Agent leaped from his kneeling position over the switch. He must not be found here, whether by bandit members or police. There was much to be done, a fresh lead he believed he could follow, a new line of action to pursue. He flung toward the window soundlessly on his rubber-soled shoes. He opened a side of the casement with quick care, stepped through into the darkness of a court as the unseen assassin had done. A moment more and the shadows of the night had swallowed him completely.
HE emerged from shadow fifteen minutes later to cross the rear yard of an ancient brownstone house. He had climbed fences, come through other yards to get here. Light from a single large window in the house before him cast dim illumination on the stone flagging at his feet. The Agent looked like a flitting ghost as he moved forward. He was still disguised, as Lorenzo Courtney. His eyes were raised to the window above. There was a look of intense concentration on his face.
For a man’s head moved across the window, turned and moved again. Some one was pacing restlessly in the lighted room, some one who could not keep still, though the hour was late and the rest of the house was dark.
The Agent slipped through an alley at the building’s side. He passed into the quiet street. Here he turned and silently mounted a flight of steps. There was a door before him and a bell button to press, but he did not touch the latter. His set of oddly shaped chromium tools came out. Under the pencil-thin beam of a tiny electric flash he probed in the keyhole.
So quickly and silently that the pacing man was unaware. Agent “X” entered the hallway of the house. He moved directly toward the rear, toward that single lighted room. His eyes were gleaming, his whole body was alert, and in his right hand was the gun he had taken from the mysterious killer who had come to Vivian de Graf’s. But as he pushed the door before him softly open, he held the weapon behind him.
The man in the room was thin, stoop-shouldered, with the look of a scholar about him. His gaunt face had a sickly, ghastly pallor. When he saw what appeared to be Lorenzo Courtney standing specterlike in the door he gasped and crouched back.
A thin smile curved the Agent’s lips. He was watching the other’s actions intently. And he had learned from them what he wanted to know. “I see that you recognize me, de Graf!”
The man who had been pacing the lighted laboratory in the old-fashioned house, leaned against a chair and passed a shaking hand across his face. He looked ten years older than when the Agent had last seen him. He raised haggard eyes, stared at the Agent dully.
“I don’t know what you mean,” he said. “I don’t know who you are. Get out of here — before I call the police.”
The Agent’s answer came relentlessly. “Emil de Graf, you’re lying. I recognized you when we fought — even though I couldn’t see you! And this is your gun.”
He thrust the weapon into sight, saw the scientist start guiltily.
“It’s the gun you killed your wife with. You are a murderer, de Graf — the murderer of your own wife!”
The face of de Graf had become grayer still. He was swaying on his feet, staring dazedly at his accuser, and Agent “X” continued:
“I know your motive. You were jealous, de Graf — insanely jealous. Behind that pretended calm of yours, behind that tolerance you professed, you were angry at your wife’s interest in other men. That’s why you killed her!”
Emil de Graf clenched his fists. “I should have killed you, too, fool that I was!” he cried. Then added hoarsely: “For God’s sake who are you? What do you want?”
The Agent’s answer was to walk slowly forward, the gun pointed at de Graf. His stare had the inexorable quality of Fate itself.
“Then you admit it,” he said quietly. “You admit you killed your wife!”
The scientist cringed, backed away. “No! No!” he gasped. “I admit nothing. You can’t have me arrested. They can’t send me to the chair. There’s no proof—” He broke off, breathing heavily, and stood as though transfixed by the Agent’s level, accusing stare.
“You are a scientist, de Graf,” “X” said quietly. “You know that, given certain facts, you can discover the truth about natural phenomena. It is the same for human actions. I know that you were jealous of your wife. I know you tried once to throw acid in her face, so that other men would not find her beautiful. I know that when your attempt to mar her beauty failed, you became desperate to the point of madness. Can you deny that?” The Agent stepped closer to de Graf. “I know that you came to Vivian de Graf’s apartment an hour ago. I fought with you in the darkness. Your wife lies dead in that room now, shot through the heart. Here is the gun from which the shot was fired. Your gun, de Graf! You killed your wife!”