When Halloway stepped closer, Gordon sensed the movement and looked in his direction. Surprised, he took off the earphones and pushed his glasses higher on his nose.

“Didn’t I lock the door? I meant to lock the door.”

“Just checking to see that everything’s okay.”

“Of course it is. Why wouldn’t it be?” Gordon asked defensively.

“That’s what they pay me to find out.”

Halloway heard a noise coming from the headphones that Gordon had set on the table. It was faint compared to when it had come through the speakers during the afternoon. Even so, he could tell that it sounded quite different now, no longer a persistent crackle but a series of wavering tones pitched at various levels, some rising while others descended, many of them occurring in high and low unison.

They had a subtle, sensual quiver. Their languid, arousing rhythm made him step forward.

“Sounds like music,” he said.

“I don’t mean to be rude, but you need to get out of here,” Gordon responded. “I have work to do.”

Halloway held up his hands. “Sure. Sorry to disturb you, Gordon. Like I said, I was just checking.”

As he stepped back, the noises from the earphones changed again, sounding definitely like music. But it was unlike any music he had ever heard.

As a teenager, he’d dreamed about becoming a rock star. He’d had a garage band and still played an electric guitar damned well. He knew about major and minor keys and four-four and three-four beat patterns. But this music didn’t have any key he’d ever heard, and it sure didn’t have any beat pattern that he recognized. Faint as it was, the music floated and dipped, glided and sank. The notes merged and separated in a rhythm that was almost like the way he breathed if he were on R & R, lying on a beach in Mexico, enjoying the salt smell of the air, absorbing the warmth of the sun.

“I don’t know what that is, but it’s the most beautiful thing I ever heard.”

Gordon took off his glasses, and to Halloway’s surprise, he didn’t protest again. Instead, when he spoke, it seemed as if he felt relieved to do so, to share his discovery with someone.

“It is beautiful,” he said.

“Why didn’t we hear it this afternoon?” Halloway asked.

“I have no idea. Whatever this is, it happens only after the sun goes down.”

“And you hear that every night?”

“No. Not like that. Until two nights ago, it was always faint and fuzzy, sort of hovering behind the static. I needed to do a lot of electronic filtering to get a sense of what it sounded like.”

“What happened two nights ago?”

“Your guess is as good as mine. But all of a sudden, that’s what I started hearing.”

“I can’t hear it very well,” Halloway said. “Why don’t you turn on the speakers?”

Gordon hesitated, evidently concerned that doing so would violate his orders. But then he shrugged as if to say, What the hell; I can’t keep this to myself any longer, and flicked a switch.

Instantly the floating, gliding, sailing music filled the room, making Halloway feel as if he were standing on a cushion of air. The instruments-whatever they were-had a synthesizer quality that made them impossible to identify. Perhaps it was only his imagination, but the wave-like tones seemed to drift into his ears like the arousing whisper of a woman pressed against him.

“My God, that’s beautiful,” he repeated. “What’s causing it?”

“We’ve been trying to figure that out since this place was built.” Gordon paused, then added, “And apparently a lot longer than that.”

Those last words were cryptic, but before Halloway could ask about them, Taggard appeared in the doorway.

“What kind of radio station is that? I’ve never heard anything like it. Is it on the Internet? How do I download that music?”

“If you tried to record it, somebody would have to shoot you,” Gordon said.

Taggard looked surprised.

“That’s not a joke,” Gordon told him.

Halloway barely paid attention to what they were saying. He felt the music drifting around him and then inside him, becoming part of him. The cushion of air on which he seemed to float became even softer. At the same time, the headache he’d been struggling with finally emerged from the hole where he’d managed to suppress it, like something that had festered until it couldn’t be denied.

The pain was beautiful.

The U.S. Army Intelligence and Security Command, known as

INSCOM, is one of the few branches of the U.S. military that is also a branch of a civilian organization, specifically the National Security Agency, the world’s largest electronic intelligence-gathering service. Although INSCOM maintains several bases, the one affiliated with the NSA is located at Fort Meade, Maryland, where the NSA is headquartered.

From his office window, Col. Warren Raleigh could see a mile away to the NSA’s headquarters, a tall complex of buildings topped by a vast array of antennae and microwave dishes. Two massive black structures dominated the group. During the day, their shiny dark windows reflected the five thousand cars that sat in the sprawling parking lots that surrounded them.

Raleigh thought that the reflection was appropriate. While the NSA’s occupants could see out, no one could see in. And the clandestine nature of the agency was represented in another way-although the buildings were huge, there were even more acres of space concealed underground.

His own office was located in a three-story building designed to look bland and unimposing. A metal plaque next to the entrance read, ENVIRONMENTAL WIND AND SOLAR DEVELOPMENT FACILITY, suggesting that the work inside was devoted to finding cheap, renewable sources of energy for the government and the military. In actuality, the plaque was one of Raleigh’s jokes. The idea that the government and the military would be interested in cost-cutting or ecological is- sues was laughable. To him, the E, W, and S of Environmental Wind and Solar actually stood for Experimental Weapons Strategy.

Many of the projects under development in the building were only tangentially related to the NSA’s task of gathering intelligence via electronic means, but some-such as the efforts to create lethal rays derived from the microwave beams that transmitted cell-phone messages-were logical extensions of the NSA’s tools. So were the experiments to develop communications satellites capable of firing laser beams toward enemy positions.

But when it came to hispersonal choice of weapons, as far as Raleigh was concerned, nothing equaled the feel of a firearm. The second of the building’s five underground levels featured an extensive gun range, part of which was a so-called shooting house with a maze designed to look like corridors and rooms in an ordinary apartment complex or office building. Along each corridor and within each room, potential threats lurked unseen. As life-sized targets popped up unexpectedly, the objective was to identify them correctly and eliminate armed opponents without injuring innocent bystanders. And the goal was to do so in the shortest possible time, usually no more than two minutes.

On this Thursday in early June, at 9 in the evening, Raleigh was prepared to beat his own record.

“With your permission, Colonel.”

“Do your job, Sergeant Lockhart.”

“Yes, sir.”

Lockhart, a bull of a man, shook Raleigh violently, then spun him.

“You can do better than that, Sergeant!”

“Yes, sir!”

The sergeant shook Raleigh so hard that the colonel’s teeth knocked together. Then Lockhart spun him so forcefully that the colonel had the sense of being in a centrifuge. For a moment, he wondered if the sergeant might be enjoying his work too much.

Abruptly Lockhart let go of him, thrust an M4 into his hands, and shoved him into the shooting house.

The sergeant had, indeed, done his job. Raleigh felt so disoriented that the floor seemed to ripple and the walls to tilt. His heart rushed, and his vision wavered.