"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.