Marxman smiled a little. He drew from his vest pocket a small capsule, like a quinine capsule. It looked like some sort of dsypepsia medicine he carried for use after meals.

"The formulae are on onion-skin paper, in this capsule. If ever I am threatened for them, I swallow them. The capsule dissolves in my stomach - and so do the formulae! I hope the necessity for swallowing them doesn't arise, for it would take me six wasted months to rediscover a few of the obscure chemical combinations in the formulae. But it can be done if necessary."

Harley nodded. "As safe a way as any, I think. Well, goodnight, Marxman. Take care of yourself, and for G.o.d's sake give the United States first chance at your gas and antidote when its worked out."

"I am American," was Marxman's simple answer. "I have worked in France because a colleague there has just the laboratory equipment I needed. That's all. My own country gets the invention when it is completed, as a matter of course."

The two men shook hands. Harley left Marxman's cabin.

Marxman stared at the little capsule in his hand, which contained the nucleus of the mightiest war weapon ever devised. Then he slipped it into his vest pocket again.

The night was warm, almost stuffy. He lit a cigar, put on a plaid cap, and went up on deck....

At that moment, in the salon at the opposite end of the ship, from which he had not stirred all evening, a man who looked like a high school princ.i.p.al but was really a.s.sistant Secretary of War Harley, was talking in low tones with his secretary, a good-looking young fellow of twenty-eight.

"I hear Marxman is on board with an interesting invention," the secretary was saying. "Are you going to see him?"

"By all means," said Harley. "I think a little later in the evening."

Marxman pa.s.sed the windows of the salon without looking in. a.s.sistant Secretary of War Harley had already seen him, he thought. It never occurred to him that a man could make up like Harley so exactly as to fool him - he was well acquainted with the man - and then proceed to pump him dry of details concerning his latest invention.

He walked to the rail, fingers touching the capsule in his vest pocket.

Sea calm as a pond. Great ship like a ghost vessel floating over it. Moon pouring down a peaceful but somehow eery white flood.

From the stern came strains of music as the ship's orchestra played for those in evening dress who cared to dance. From the salon nearest to where Marxman stood by the rail came a burst of laughter as members of a salesmen's convention to Europe laughed over a Joke.

Right behind Marxman there was an iron staircase leading up to the boat deck. From that deserted upper deck a figure appeared. It blotted out the faint light at the head of the stairs. It began to descend, slowly, without a sound, like a great snake slithering down on its prey.

Once Marxman turned for a moment. The black figure became a motionless blot on the staircase. Marxman looked out over the sea again. Then the figure recommenced its crawling descent. A faint streak of light from the drawn shutters of a near-by cabin flicked over it.

It revealed a form in a black cloak with a black hat pulled low. That was all. The face could not be seen. Yet evil radiated from the form as heat radiates from black-hot iron.

The black figure reached the deck and took two rapid strides toward the inventor....

Gay laughter from the salon - casual music from the dance floor - and on the deck, death!

Marxman tried to cry out. A steely arm hooked around his throat prevented a whisper from coming from his lips. His hand darted for his vest pocket and he raised the capsule to his lips and took it into his mouth.

The arm around his throat was replaced by steely hands. He couldn't swallow. His face grew blue, purple, with eyes starting from their sockets as he fought for breath. Then his writhing body became still. It hung from the iron grip of the hands around his throat.

One of the hands shifted. Fingers, gloved, pried open Marxman's Jaws. They took the melting capsule from his mouth. Then the dark figure heaved upright.

A thing like a badly tied bundle of rugs went over the ship's rail. There was a faint splash, almost inaudible in the plashing of the ship's progress.

The dark figure watched Marxman's body float astern like a drift log in the white wake of the moonlight. Then it turned, and melted into the darkness of the nearest companionway. And with it went the formulae of the new gas - and its partly perfected antidote.

2.

On a hill fronting the sh.o.r.e of the bay among great estates forming the cream of the big houses in the wealthy resort town on Red Bank, New Jersey, was the home of Linton R. Yates. A thirty-room mansion, it crowned the hill like a coronet of gray, cut stone.

At the moment it was dark. No lights showed from any window, even the windows in the servants' quarters. It looked empty. But it wasn't. In the darkness of the side driveway a roadster stood. The roadster had been driven there, alone, by Linton Yates himself. And Linton Yates was at present in the bas.e.m.e.nt of the house.

Down there, with none of the electric light showing from any barred and steel-shuttered bas.e.m.e.nt windows, he stood beside the square furnace at the end wall. His withered old hand went out. He touched a small, discolored patch in the wall next to the back of the furnace. A section of the wall hinged out.

Gray bearded, wizened, crafty-looking, the rich man stared furtively around him before he stepped into the hidden bas.e.m.e.nt room revealed by the swinging back of the concealed door. As he entered the room he touched another discolored patch in the stone wall, and the door closed after him.

There was a great safe door in the floor of the ten-by-ten cube. So large was it that it almost formed the floor of the room. Rubbing his hands together with a dry, rasping sound, Yates walked over the safe door to a big k.n.o.b in its center. He twirled that to the required combination, walked off the door, and threw a small switch.

There was a hum as a half-horsepower electric motor spun gears that slowly raised the ponderous door. Yates went down two steps into the safe. Here was a great heap of small, dirty yellow bars, and a square steel box. The yellow bars were gold; tons of the stuff, h.o.a.rded here by Yates against the day when the country would return to the gold standard - at a new and high dollar-value that should give him two dollars for every one he had spent for the precious metal. The steel box....

Yates chuckled aloud as he pa.s.sed the bars of gold and went to the box. It weighed perhaps a hundred pounds. It was with a panting effort that the wizened old man managed to open the lid. With the lid opened, he crooned aloud, as a man might talk to an adorned pet.

A coruscating, varicolored fire came from within the box. It was cold fire. Yates plunged his hands in and lifted them. The fire trickled back down between his fingers and into the box again. The fire of diamonds, hundreds of them, unset but perfectly cut.

Diamonds and gold! The two commodities, particularly gold, that always have at least some solid worth, no matter to what low price other commodities sink.

"With these," whispered Yates, eyes gleaming, "I am secure. No man or form of government can harm me - make me poor."

He let diamonds trickle through his claw-like fingers again, then stiffened suddenly.

But his stiffening was not that of alarm, nor was it that of listening. He stared straight ahead of him, at the steel and copper wall of the sunken safe. But he did not see that wall. His filmed eyes were glazing rapidly, as the eyes of a man glazing in death. His body was as stiff suddenly, and for no apparent reason, as a thing of wood.

For perhaps a full minute he stood there, bent over the box a little, with the last of the diamonds trickling from his cupped hands to the strong-box. Then slowly, he began to sag toward the floor. He sank to his knees, his rigid stare still centered on the safe wall. He fell, like a falling log, p.r.o.ne beside the treasure box.

He was dead. A glance could reveal that fact. But in a moment it was revealed that his death was not the most horrible part of the unseen drama to be played in the sunken safe.

The dead body abruptly began to lose its solidarity of outline. Its demarcations became blurred, as the surface of hot stone is blurred when heat waves shimmer up from it. And as the outlines became more and more blurred, they commenced to dwindle.

The dead body shrank, like wool in hot water. It got smaller till it was like the form of a doll dressed in doll's clothes to resemble an old man. And then - there was nothing in the safe but the dirty bars of gold and the small box of gems. At least, a glance would have intimated that there was nothing. Only a careful look would have shown, on the floor beside the box, a tiny thing like a watch-charm shaped in human form.

That was at eleven-thirty at night. At twelve, a big closed car drew up behind Yates' roadster under the side portico. The closed car had come thirty miles in thirty minutes. From it descended a figure cloaked in black, with a black hat on its head, the brim of which hid all trace of its features.

The figure worked an instant with the lock of the side door, opened it, and walked in darkness to the bas.e.m.e.nt stairs. Beside the furnace a gloved hand - gloved in red instead of in more conventional hue - went out and touched the discolored patch.

Leisurely the figure went into the hidden bas.e.m.e.nt room. It lifted the box of gems first. The box was borne to the big closed car. Then, bar by bar, the gold followed, carried by the dark figure as though the two hundred and fifty pounds each weighed were scarcely more than a normal load.

With plenty of time between trips, the big car was loaded till it sagged drunkenly low on its springs. Then it was backed out of the drive under the red-gloved hands of the dark form at the wheel.

It slid soundlessly into the main road, turned, and took the wide pike toward New York City....

It was at three in the morning when the Red Bank chief of police, a dark-faced, slow-moving man named Carlisle who was high in New York's detective bureau, and a man with black hair and steel-gray eyes, entered the sunken safe in the hidden bas.e.m.e.nt room.

"See?" said the Red Bank chief. "Its all like I phoned, you Carlisle. Yates' roadster is at the side door, lights out and motor cold. The cook next door reported seeing the old man drive in, and after he'd been in the place two hours, with no lights on, she had sense enough to think something funny was going on. So she phoned me. But I get here and find this safe open and empty, and no sign of Yates! Now where the h.e.l.l is he? He ain't in the house, and he ain't on the grounds. He couldn't have gone far without his roadster. And anyhow, his safe's cleaned. It must have had something pretty valuable in it. He certainly didn't clean it out himself and then Just walk away somewhere leaving it wide open!"

The tall man with the coal-black hair and the gray eyes stopped suddenly. He picked up something from the floor, near a square in the dust that looked as though a box had rested there recently.

"What'd you find, Keane?" Carlisle asked.

Ascott Keane, probably the most competent detective alive, though few knew him as anything but a polo-playing rich man's son, faced Lieutenant Detective Carlisle.

"Nothing but a burnt match," he said, holding out a paper match with a charred end. "I don't think it will tell us much."

He gave the charred match to Carlisle.

But into his coat pocket went another small object, hardly bigger than the match, which he had picked up from the floor at the same time and palmed.

Carlisle grunted at the match, then looked expectantly at Ascott Keane.

"Well," he said, "you once told me to get in touch with you any time an especially mysterious crime was done. This is crime, sure enough. And, d.a.m.ned if it isn't mysterious enough. Think your pal, Doctor Satan, did it?"

Keane shrugged.

"There undoubtedly was something of great value in this carefully concealed strong-room. There must have been a great deal of it. Probably h.o.a.rded gold. Certainly Yates wasn't able to carry it away; he was an old man, rather feeble. Somebody got rid of him, somehow, when he was down here counting over his buried treasure! And, from the complete absence of all clues, I'd say the person clever enough to do that might have been - Doctor Satan."

Carlisle stared curiously at Keane. Keane's face was as calm as a poker-player's. But it was to be noted that fine beads of perspiration were on his face, and that his cheeks were not quite as calm as his expression. Hard marks ridged them.

"That all you got to tell me?" he said.

"That's all for the moment. I think I'll run along ---"

"But you just came!" Carlisle said, disappointed and a little suspicious. "You haven't looked around at all."

"Looking around won't get you anywhere - if this is the work of Doctor Satan. And I'm sure it is. A lot of quiet study in a secluded spot is more to the point. I'm off the indulge myself in that now."

He nodded to the two men, and left the bas.e.m.e.nt.

Behind Yates' car was the police car the Chief and Carlisle had come in. Behind that was Keane1s long-low-hooded sedan with its streamlines and its hundred and thirty miles an hour of speed under its hood.

Beside the driver's seat was a girl, waiting for him. She was tall and lithe. Her dark blue eyes, in the light from the dash, softened as they turned on him. Her hair, escaping in a few tendrils from under a smart, small hat, was coppery brown. This was Beatrice Dale, Keane's secretary. No, more than secretary! She was his able a.s.sistant, his right hand man. More than once in his pursuit of the monster of crime who called himself Doctor Satan, Keane had reached the point where he could hardly have carried on without her aid.

"What did you find?" she said eagerly, as he took the seat beside her and started the motor. "Was it Doctor Satan's work?"

Wordlessly, in answer, Keane handed her the small thing he'd picked up from the floor in the rifled strong-room. Then he slid into reverse gear as she looked at it.

"Ascott, what is it?" Beatrice said. "It looks like a tiny doll. Yet it gives me the creeps somehow. It seems to be made of rubber or some such stuff. A little doll, hardly more than, half an inch long. What is it?"

Keane tooled the car onto the highway and started along the New York pike. He glanced somberly at her.

"What is it? Well, it isn't a doll. Here, give it back to me before I tell you."

He took it from her fingers and put it back into his pocket.

"That," he said, "is a man. Not a doll. A dead man!"

"What ---" Beatrice faltered.

"It's the remains of Linton R. Yates. Now, you're not going to faint I wouldn't have told you if I'd thought you were apt to do anything silly."

Beatrice Dale straightened her swaying body into the seat. She drew a deep breath, and her voice was measurably calm as she said: "You flatter my nerves, I'm afraid. My G.o.d! A dead man! And I held it!"

It was notable that she didn't question for an instant the statement that a thing like a tiny doll, which could be held in the palm of her hand, was, impossibly, a dead body. She had worked with Keane long enough to know that his statements were apt to be infallible. And the feel of the little thing that "had given her the creeps" bore out his fantastic declaration.

"Yes," he said as the car leaped toward eighty miles an hour, "that little thing is Linton Yates, retired oil magnate. Can you imagine his loving family gathered around that, during a burial ceremony. Like burying a watch-charm with all dur pomp and surroundings!"

"Then it was Doctor Satan!" n.o.body else on earth could have done so hideous and bizarre a thing! But how ---"

She stared at him, still pale, eyes wide.

Keane frowned at the night, into which they were boring at express train speed.

"I think I know how. I'll make sure when we've got to my library at home."

That was at a little after three. At four, they stood in Keane's book-lined library beside the great ebony desk at which he had sat studying so many problems arising from the ghastly genius of Doctor Satan.

Keane was reading a two-year-old scientific paper ent.i.tled "The Possibilities of a Death, or Disintegrating, Ray," by someone named Barnard Hallowell: "The death ray, so-called from popular speculations of a disintegrating device by the public press, is not at all an impossible dream. I am working on some such device now. I have come close to its solution several times. As none of the features of my invention has yet been perfected to the point where they can be patented, I will naturally not reveal particulars to you. But I can describe the result of the machine when - and if - it is completed.

"My apparatus could be pointed and aimed as accurately as any gun, so that the ray it emits can kill one person, and one person, alone, at a distance up to forty miles. Or the ray could be so diffused that all things within a forty-degree arc of its muzzle (at a lesser distance, however) would die. The ray strikes instantly dead the thing it is loosed upon. Then it further disintegrates the flesh of the carca.s.s by causing the molecules to split apart and stream away, through solid objects around it, and eventually, into empty s.p.a.ce. How can I know this, when I never yet quite completed a machine? My only answer unfortunately, not provable since I cannot let anyone see the fruits of my experiments to date, is that I have come near enough to the solution to what the problem is in effect, similar to what I describe, to begin on bodies of animals in my laboratory...."

Keane closed the paper, and looked at Beatrice.

Her blue eyes were level with concentration. She stared at the paper in his hand, then at his face.

"Doctor Satan got to the man who wrote that paper, Bernard Hallowell," she said. "Since he wrote it, he has completed the death-ray machine. Doctor Satan forced the secret of it from him. That is what the little figure you picked up in Yate's safe means."

Keane slowly shook his head. On his forehead again appeared fine drops of sweat. And again, hard muscle ridged out on his lean cheeks.

"No, Beatrice," "It means more than that - much more. You see, Bernard Hallowell is dead. He died two years ago, just after reading this paper before a meeting of the American Scientific Inst.i.tute."

Beatrice stared at him, color slowly draining from her face as she vaguely sensed something of what was in his mind.

"Bernard Hallowell, the one man on earth capable of doing to a human body what was done to Yates, is dead. Yet Doctor Satan got from him the secret of the death ray - which was not quite completed when he died. That can mean only thing: "Doctor Satan has found out how really to do that which charlatans and self-deluded investigators have often claimed baselessly they could do - communicate with the dead."