"I have just turned out a camouflage which is the most perfect yet discovered. It was designed for application to guns and equipment only. I'd never thought of trying to cover a human body with it, but I am sure it can be done."

"But ... invisible ..." muttered Forsyte, glancing askance at Winter.

"There's no time for argument," said the Secretary crisply. "The question is, shall we give this man permission to try the apparently impossible?"

All heads nodded, though in all eyes was doubt. The Secretary turned to the scientist.

"You are aware of the risk you run? You realize that if you are caught, we cannot recognize you--that we must disclaim official knowledge of your work, and leave you to your fate?"

Thorn nodded.

"Then," said the Secretary, his voice vibrant, "yours is the mission. And on your effort hangs the fate of your country. Now--what help will you require?"

"Only the assistance of one man," said Thorn. "And, since secrecy is vital, I'm going to ask you, sir, to be that man."

The Secretary smiled; and with that smile he seemed to be transformed from a great leader of affairs into a kindly, human individual. "I am honored, Mr. Winter," he said. "Shall we go at once to your laboratory?"

* * * * *

In the great laboratory room, the Secretary glanced about almost uneasily at the crowding apparatus that was such an enigma to one untrained in science. Then his gaze returned to Winter's activities.

Thorn was carefully stirring fluids, poured drop by drop from various retorts, in a mixing bowl. All the fluids were colorless; and they combined in a mixture that had approximately the consistency of thin syrup. To this, Thorn added a carefully weighted pinch of glittering powder. Then he lit a burner under the bowl, and thrust into the mixture a tiny, specially constructed thermometer.

"You can really make yourself invisible?" breathed the Secretary.

"I can," said Thorn, "if the blisters don't upset my calculations by making my body surfaces too moist for this stuff to stick to. I'm going to have you paint me with it, you see, and it was never intended to cover flesh."

He regulated the burner anxiously, and then began to take off his clothes.

"Ready," he said at last, glancing at the thermometer and turning off the burner. He stood before the wondering Secretary, a fine, muscular figure. "Take this brush and cover me with the stuff. And be sure not to miss any of me!"

And then the Secretary saw why Thorn had said the colorless paint was never intended to be applied to human flesh. For it was still seething and smoking in the cauldron.

"Good heavens!" he said. "Don't you want to wait till it cools a little?"

"Can't," said Thorn. "It has to be applied hot or it loses its flexibility."

The Secretary dipped the brush and began to paint the naked flesh of the scientist. Not a quiver touched that flesh as an almost microscopically thin, colorless layer formed into a film after the brush strokes. But the Secretary's fingers shook a little.