"Here's the audio," Comroe said. He pressed another button and the audio version of the signal filled the room. It was a steady mechanical grinding with a repetitive metallic click.

Manchek nodded. "An engine. With a knock."

"Yes sir. We believe the van radio is still broadcasting, and that the engine is still running. That's what we're hearing now, with the static screened away."

"All right," Manchek said.

His pipe went out. He sucked on it for a moment, then lit it again, removed it from his mouth, and plucked a bit of tobacco from his tongue.

"We need evidence," he said, almost to himself. He was considering categories of evidence, and possible findings, contingencies…

"Evidence of what?" Comroe said.

Manchek ignored the question. "Have we got a Scavenger on the base?

"I'm not sure, sir. If we don't, we can get one from Edwards."

"Then do it." Manchek stood up. He had made his decision, and now he felt tired again. An evening of telephone calls faced him, an evening of irritable operators and bad connections and puzzled voices at the other end.

"We'll want a flyby over that town," he said. "A complete scan. All canisters to come directly. Alert the labs."

He also ordered Comroe to bring in the technicians, especially Jaggers. Manchek disliked Jaggers, who was effete and precious. But Manchek also knew that Jaggers was good, and tonight he needed a good man.

At 11:07 p.m., Samuel "Gunner" Wilson was moving at 645 miles per hour over the Mojave Desert. Up ahead in the moonlight, he saw the twin lead jets, their afterburners glowing angrily in the night sky. The planes had a heavy, pregnant look: phosphorus bombs were slung beneath the wings and belly.

Wilson's plane was different, sleek and long and black. It was a Scavenger, one of seven in the world.

The Scavenger was the operational version of the X-18. It was an intermediate-range reconnaissance jet aircraft fully equipped for day or night intelligence flights. It was fitted with two side-slung 16mm cameras, one for the visible spectrum, and one for low-frequency radiation. In addition it had a center-mount Homans infrared multispex camera as well as the usual electronic and radio-detection gear. All films and plates were, of course, processed automatically in the air, and were ready for viewing as soon as the aircraft returned to base.

All this technology made the Scavenger almost impossibly sensitive. It could map the outlines of a city in blackout, and could follow the movements of individual trucks and cars at eight thousand feet. It could detect a submarine to a depth of two hundred feet. It could locate harbor mines by wave-motion deformities and it could obtain a precise photograph of a factory from the residual heat of the building four hours after it had shut down.

So the Scavenger was the ideal instrument to fly over Piedmont, Arizona, in the dead of night.

Wilson carefully checked his equipment, his hands fluttering over the controls, touching each button and lever, watching the blinking green lights that indicated that all systems were in order.

His earphones crackled. The lead plane said lazily, "Coming up on the town, Gunner. You see it?"

He leaned forward in the cramped cockpit. He was low, only five hundred feet above the ground, and for a moment he could see nothing but a blur of sand, snow, and yucca trees. Then, up ahead, buildings in the moonlight.

"Roger. I see it."

"Okay, Gunner. Give us room."

He dropped back, putting half a mile between himself and the other two planes. They were going into the P-square formation, for direct visualization of target by phosphorus flare. Direct visualization was not really necessary; Scavenger could function without it. But Vandenberg seemed insistent that they gather all possible information about the town.

The lead planes spread, moving wide until they were parallel to the main street of the town.

"Gunner? Ready to roll?"

Wilson placed his fingers delicately over the camera buttons. Four fingers: as if playing the piano.

"Ready."

"We're going in now."

The two planes swooped low, dipping gracefully toward the town. They were now very wide and seemingly inches above the ground as they began to release the bombs. As each struck the ground, a blazing white-hot sphere went up, bathing the town in an unearthly, glaring light and reflecting off the metal underbellies of the planes.

The jets climbed, their run finished, but Gunner did not see them. His entire attention, his mind and his body, was focused on the town.

"All yours, Gunner."

Wilson did not answer. He dropped his nose, cracked down his flaps, and felt a shudder as the plane sank sickeningly, like a stone, toward the ground. Below him, the area around the town was lighted for hundreds of yards in every direction. He pressed the camera buttons and felt, rather than heard, the vibrating whir of the cameras.

For a long moment he continued to fall, and then he shoved the stick forward, and the plane seemed to catch in the air, to grab, and lift and climb. He had a fleeting glimpse of the main street. He saw bodies, bodies everywhere, spread-eagled, lying in the streets, across cars…

"Judas," he said.

And then he was up, still climbing, bringing the plane around in a slow arc, preparing for the descent into his second run and trying not to think of what he had seen. One of the first rules of air reconnaissance was "Ignore the scenery "; analysis and evaluation were not the job of the pilot. That was left to the experts, and pilots who forgot this, who became too interested in what they were photographing, got into trouble. Usually they crashed.

As the plane came down into a flat second run, he tried not to look at the ground. But he did, and again saw the bodies. The phosphorus flares were burning low, the lighting was darker, more sinister and subdued. But the bodies were still there: he had not been imagining it.

"Judas Priest," he said again. "Sweet Judas."

The sign on the door said DATA PROSSEX EPSILON, and underneath, in red lettering, ADMISSION BY CLEARANCE CARD ONLY. Inside was a comfortable sort of briefing room: screen on one wall, a dozen steel-tubing and leather chairs facing it, and a projector in the back.

When Manchek and Comroe entered the room, Jaggers, was already waiting for them, standing at the front of the room by the screen. Jaggers was a short man with a springy step and an eager, rather hopeful face. Though not well liked on the base, he was nonetheless the acknowledged master of reconnaissance interpretation. He had the sort of mind that delighted in small and puzzling details, and was well suited to his job.

Jaggers rubbed his hands as Manchek and Comroe sat down. "Well then," he said. "Might as well get right to it. I think we have something to interest you tonight. " He nodded to the projectionist in the back. "First picture."

The room lights darkened. There was a mechanical click, and the screen lighted to show an aerial view of a small desert town.

"This is an unusual shot," Jaggers said. "From our files. Taken two months ago from Janos 12, our recon satellite. Orbiting at an altitude of one hundred and eighty-seven miles, as you know. The technical quality here is quite good. Can't read the license plates on the cars yet, but we're working on it. Perhaps by next year."

Manchek shifted in his chair, but said nothing.

"You can see the town here," Jaggers said. "Piedmont, Arizona. Population forty-eight, and not much to look at, even from one hundred and eighty-seven miles. Here's the general store; the gas station- notice how clearly you can read GULF- and the post office; the motel. Everything else you see is private residences. Church over here. Well: next picture."

Another click. This was dark, with a reddish tint, and was clearly an overview of the town in white and dark red. The outlines of the buildings were very dark.

"We begin here with the Scavenger IR plates. These are infrared films, as you know, which produce a picture on the basis of heat instead of light. Anything warm appears white on the picture; anything cold is black. Now then. You can see here that the buildings are dark- they are colder than the ground. As night comes on, the buildings give up their heat more rapidly."

"What are those white spots?" Comroe said. There were forty or fifty white areas on the film.

"Those," Jaggers said, "are bodies. Some inside houses, some in the street. By count, they number fifty. In the case of some of them, such as this one here, you can make out the four limbs and head clearly. This body is lying flat. In the street."

He lit a cigarette and pointed to a white rectangle. "As nearly as we can tell, this is an automobile. Notice it's got a bright white spot at one end. This means the motor is still running, still generating heat."

"The van," Comroe said. Manchek nodded.

"The question now arises," Jaggers said, "are all these people dead? We cannot be certain about that. The bodies appear to be of different temperatures. Forty-seven are rather cold, indicating death some time ago. Three are warmer. Two of those are in this car, here."

"Our men," Comroe said. "And the third?"

"The third is rather puzzling. You see him here, apparently standing or lying curled in the street. Observe that he is quite white, and therefore quite warm. Our temperature scans indicate that he is about ninety-five degrees, which is a little on the cool side, but probably attributable to peripheral vasoconstriction in the night desert air. Drops his skin temperature. Next slide."

The third film flicked onto the screen.

Manchek frowned at the spot. "It's moved."

"Exactly. This film was made on the second passage. The spot has moved approximately twenty yards. Next picture.

A third film.

"Moved again!"

"Yes. An additional five or ten yards."

"So one person down there is alive?"

"That," Jaggers said, "is the presumptive conclusion."

Manchek cleared his throat. "Does that mean it's what you think?"

"Yes sir. It is what we think."