Air molecules could penetrate the shield freely, but, small though they were, the dust particles were large enough to be stopped. David could see the process with the naked eye. As each dust particle struck the shield, it was halted and the energy of its motion converted into light, so that at its point of attempted penetration a tiny sparkle showed. David found his body an ocean of such sparkles crowding one another, all the brighter as the Martian sun, red and smokily dim through the dust, allowed the ground below to remain in semi-darkness.

David slapped and brushed at his clothing. Dust clouds arose, too fine to see even if the cloudiness of the shield had not prevented sight in any case. The dust left but could not return. Gradually he became almost clear of the particles. He looked dubiously at the scooter and attempted to start its motor. He was rewarded only by a short, grating noise and then silence. It was to be expected. Unlike the sand-cars, scooters did not, could not, have enclosed motors.

He would have to walk. The thought was not a particularly frightening one. The farm dome was little more than two miles away and he had plenty of oxygen. His cylinders were full. The Martians had seen to that before sending him back.

He thought he understood them now. They did know the dust storm was coming. They might even have helped it along. It would be strange if, with their long experience with Martian weather and their advanced science, they had not learned the fundamental causes and mechanisms of dust storms. But in sending him out to face the storm, they knew he had the perfect defense in his pocket. They had not warned him of either the ordeal that awaited him or of the defense he carried. It made sense. If he were the man who deserved the gift of the force-shield, he would, or should, think of it himself. If he did not, he was the wrong man for the job.

David smiled grimly even as he winced at the touch of his clothing against inflamed skin as he stretched his legs across the Martian terrain. The Martians were coldly unemotional in risking his life, but he could almost sympathize with them. He had thought quickly enough to save himself, but he denied himself any pride in that. He should have thought of the mask much sooner.

The force-shield that surrounded him was making it easier to travel. He noted that the shield covered the soles of his boots so that they never made contact with the Martian surface but came to rest some quarter inch above it. The repulsion between himself and the planet was an elastic one, as though he were on many steel springs. That, combined with the low gravity, enabled him to devour the distance between himself and the dome in swinging giant strides.

He was in a hurry. More than anything else at the moment he felt the need of a hot bath.

By the time David reached one of the outer locks of the farm dome the worst of the storm was over and the light flashes on his force-shield had thinned to occasional sparks. It was safe to remove the mask from his eyes.

When the locks had opened for him, there were first of all stares, and then cries, as the farmboys on duty swarmed about him.

"Jumping Jupiter, it's Williams!"

"Where've you been, boy?"

"What happened?"

And above the confused cries and simultaneous questioning there came the shrill cry, "How did you get through the dust storm?"

The question penetrated, and there was a short silence.

Someone said, "Look at his face. It's like a peeled tomato."

That was an exaggeration, but there was enough truth to it to impress all who were there. Hands were yanking at his collar which had been tightly bound about his neck in the fight against the Martian cold. They shuffled him into a seat and put in a call for Hennes.

Hennes arrived in ten minutes, hopping off a scooter and approaching with a look that was compounded of annoyance and anger. There were no visible signs of any relief at the safe return of a man in his employ.

He barked, "What's this all about, Williams?"

David lifted his eyes and said coolly, "I was lost."

"Oh, is that what you call it? Gone for two days and you were just lost. How did you manage it?"

"I thought I'd take a walk and I walked too far."

"You thought you needed a breath of air, so you've been walking through two Martian nights? Do you expect me to believe that?"

"Are any sand-cars missing?"

One of the farmboys interposed hastily as Hennes reddened further. "He's knocked out, Mr. Hennes. He was out in the dust storm."

Hennes said, "Don't be a fool. If he were out in the dust storm, he wouldn't be sitting here alive."

"Well, I know," the farmboy said, "but look at Mm."

Hennes looked at him. The redness of his exposed neck and shoulders was a fact that could not be easily argued away.

He said, "Were you in the storm?"

"I'm afraid so," said David.

"How did you get through?"

"There was a man," said David. "A man in smoke and light. The dust didn't bother him. He called himself the Space Ranger."

The men were gathering close. Hennes turned on them furiously, his plump face working.

"Get the Space out of here!" he yelled. "Back to your work. And you, Jonnitel, get a sand-car out here."

It was nearly an hour before the hot bath he craved was allowed David. Hennes permitted no one else to approach him. Over and over again, as he paced the floor of his private office, he would stop in midstride, whirl in sudden fury, and demand of David, "What about this Space Ranger? Where did you meet him? What did he say? What did he do? What's this smoke and light you speak of?"

To all of wliich David would only shake his head slightly and say, "I took a walk. I got lost. A man calling himself the Space Ranger brought me back."

Hennes gave up eventually. The dome doctor took charge. David got his hot bath. His body was anointed with creams and injected with the proper hormones. He could not avoid the injection of Soporite as well. He was asleep almost before the needle was withdrawn.

He woke to find himself between clean, cool sheets in the sick bay. The reddening of the skin had subsided considerably. They would be at him again, he knew, but he would have to fight them off but a little while longer.

He was sure he had the answer to the food-poisoning mystery now; almost the whole answer. He needed only a missing piece or two, and, of course, legal proof.

He heard the light footstep beyond the head of his bed and stiffened slightly. Was it going to begin again so soon? But it was only Benson who moved into his line of vision. Benson, with his plump lips pursed, his thin hair in disarray, his whole face a picture of worry. He carried something that looked like an old-fashioned clumsy gun.

He said, "Williams, are you awake?"

David said, "You see I am."

Benson passed the back of his hand across a perspiring forehead. "They don't know I'm here. I shouldn't be, I suppose."

"Why not?"

"Hennes is convinced you're involved with this food poisoning. He's been raving to Makian and my- self about It. He claims you've been out somewhere and have nothing to say about it now other than ridiculous stories. Despite anything I can do, I'm afraid you're in terrible trouble."

"Despite anything you can do? You don't believe Hennes's theory about my complicity in all this?"

Benson leaned forward, and David could feel his breath warm on his face as he whispered, "No, I don't. I don't because I think your story is true. That's why I've come here. I must ask you about this creature you speak of, the one you claim was covered with smoke and light. Are you sure it wasn't a hallucination, Williams?"

"I saw him," said David.

"How do you know he was human? Did he speak English?"

"He didn't speak, but he was shaped like a human." David's eyes fastened upon Benson. "Do you think it was a Martian?"