up a cloud of dust. It was a very small cloud of very fine dust. Thorn at first thought nothing of it, because he was so engrossed in the conviction that here ought to be provided an entrance into the house.

The truck driver got out, took a crate from the body of the van, and went with it to the back door. After a moment of waiting, the door opened. Thorn noticed that it was opened very cautiously, only an inch or so. He caught a glimpse of a heavy chain stretched across the inch opening, and saw a strip of bearded, resolute face.

The door was unchained. The driver walked in, while the door stood open. Thorn started to glide in after him....

Mere chance made him glance at a window near the door. This window framed another bearded, resolute face. And the eyes in that face were like saucers as they stared full at Thorn!

For an instant Thorn knew icy fear. His invisibility! Had something happened to strip him of that concealing mantle? But what could have happened?

He glanced down at himself and saw the reason for the guard's saucer-eyed expression.

A little of the light cloud of dust stirred up by the truck wheels had settled over him and clung to the encasing shell. As he moved, these dust specks moved. The effect to the staring guard, Thorn realized, must be that of seeing a queer, fine dust column moving eccentrically over a grassy lawn where no dust column had any business to be.

Quickly Thorn moved toward the garage, with the eyes of the amazed guard following him. The scientist was savage at the delay; but it was vital that he rid himself of that clinging dust.

Behind the garage he broke off a feathery spray from a vine, and stroked it lightly over himself. That, too, presented a curious spectacle: a leafy branch suddenly detaching itself from the parent vine and dancing here and there in mid-air.

When the all-important task was done, Thorn raced back to the rear doorway. By great good luck it was still open. He stole in, just making it as the truck driver, staggering under a load of empty crates, came up the cellar stairs and went out to his truck.

Thorn drew a deep breath. He was inside the Arvanian Embassy. The place was a three-storied stone trap in which, if the slightest slip revealed him to its tenants, he would surely meet his death. But, anyway, he was inside! And the threatening Ziegler plans waited somewhere near at hand for him to find and take!

Even had Thorn not known in advance that trouble was brewing, he could have surmised that something sinister was being hatched in the Arvanian Embassy. For, in this big sunny kitchen five men lounged about in addition to the white-coated chef and his beardless stripling of an assistant. And each of the five had a holster strapped openly over his coat with the butt of an automatic protruding in plain sight.

Thorn looked about. Across from the great range, beside which he was standing and holding his breath for fear some one of the seven men should become aware of his presence, was the door leading to the front part of the house. He started toward that door, walking on tiptoe. A shudder crept up his spine as he tiptoed across the floor directly in front of the armed guards who would have shot him down without compunction could they have seen him. He was not yet used to his invisibility; knowing himself to be substantial, feeling his feet descend solidly on the floor, he still could hardly credit the fact that human eyes could not observe him.

He got to the door. He put out his hand to open it, then realized just in time that he could not do that. A door stealthily opening and closing again, with no apparent hand to manipulate it? Such a spectacle would start a riot!

In a frenzy of impatience, he stood beside the door, waiting till someone else should swing it open. And in a moment it chanced that the stripling assistant chef came toward him with a tray. The boy pushed the swinging door with his foot, and walked into the butler's pantry. After him, treading almost on the lad's heels, came Thorn.

The boy sat the tray down, and turned to reach into an upper shelf. The space in the pantry was constricted, and he turned abruptly. The result was that he suddenly drew back as though a hot iron had seared him, and went white as chalk. Then he dashed back into the kitchen.

"A hand!" Thorn heard him gibbering in Arvanian. "A hand! I touched it with mine! Something horrible is in there!"

With his heart pounding in his throat, Thorn leaned close to the swing-door to hear what happened next. Would there be a rush for the butler's pantry? An investigation? He eyed the farther door—the dining room door. But he dared not flee through that save as a last resort. In the dining room sounded voices; and again the sight of a door opening and closing of itself would lead to uproar.

"A hand?" he heard one of the guards say in the kitchen. "An unseen hand? Thou art empty in the head, young Gova."

There followed some jeering sentences in colloquial Arvanian that were too idiomatic for Thorn's knowledge of the language to let him understand. A general guffaw came from the rest; and, as no move was made toward the pantry, Thorn decided he was saved for another few moments.

Gasping, he raised his hand to wipe the perspiration off his forehead, then realized there was no perspiration there. His film-clogged pores could exude nothing; he had only the sensation of perspiring.

Now the problem was to get through the next door. Thoughtfully, Thorn gazed at it. He saw that this, too, was a swing-door. Further, he saw that now and then it creaked open a few inches, and swung sluggishly back. Beyond it somewhere a window was open, and spasmodic gusts moved the swinging slab of wood.

The next time the door moved with the wind, Thorn caught it and augmented the movement a bit. Twice he did that, each time swinging it back a trifle further. Next time, he figured, he could open it enough to slide into the room.

Two glimpses he had had, with the openings of the door, into the room beyond. These glimpses had showed him a great oval table on which was set the debris of afternoon tea, and around which were grouped tense, eager men. Dark of hair and complexion were these men, with the arrogant hawk noses and ruthless small eyes of the typical Arvanian. Several of them were garbed in military uniforms and armed with swords. They were talking in tones too low for Thorn to distinguish words through the film over his ears. He would have to get in there to hear them.

For the third time the wind pushed at the door. For the third time Thorn caught its edge and swung it—six inches, eight, almost enough to slip through....

"Shut thou the window!" crackled a voice suddenly. "Fool! What if some of these documents blew away?"

There was a slam, and the breeze was cut off. Thorn quickly let go of the door, and watched it fall back in place again.

He was cursing his luck when he heard the same commanding voice say: "Kori, see if there be one who listens in the butler's pantry. It seemed the door opened wider than the wind would warrant."

There was the scrape of a chair. Then the door was abruptly thrust open and coldly alert eyes in a hostile, wary face, swept over the pantry.

"No one here, Excellency," said Kori; and he returned to his place at the table.

But with him came another, unseen, to stand against the wall beside a great mahogany buffet, and to listen and watch. Kori had, not unnaturally, held the door open while he glanced around the pantry. And under Kori's outstretched arm, so close as almost to brush against his uniformed legs, had stolen Thorn.

"Then, gentlemen, it is all arranged?" said the man at the head of the oval table—a spare, elderly individual with bristling gray mustachios and smoldering dark eyes. "The plans leave for Arvania to-morrow night, to arrive in our capital city in ten days. Then day and night manufacture of the