The National Security Agency is hidden discreetly away on eighty-two rambling acres at Fort Meade, Maryland, in two buildings that together are twice the size of the CIA complex in Langley, Virginia. The Agency, created to give technical support to protect United States communications and acquire worldwide intelligence data, employs thousands of people, and so much information is generated by its operations that it shreds more than forty tons of documents every day.

It was still dark when Commander Robert Bellamy arrived at the first gate. He drove up to an eight-foot-high cyclone fence with a topping of barbed wire. There was a sentry booth there, manned by two armed guards. One of them stayed in the booth, watching, as the other approached the car. "Can I help you?"

"Commander Bellamy to see General Hilliard."

"May I see your identification, Commander?"

Robert Bellamy pulled out his wallet and removed his 17th District Naval Intelligence ID card. The guard studied it carefully and returned it. "Thank you, Commander."

He nodded to the guard in the booth and the gate swung open. The guard inside picked up a telephone. "Commander Bellamy is on his way."

A minute later Robert Bellamy drove up to a closed, electrified gate.

An armed guard approached the car. "Commander Bellamy?"

"Yes."

"May I see your identification, please?"

He started to protest and then he thought, What the hell? It's their zoo. He took out his wallet again and showed his identification to the guard.

"Thank you, Commander." The guard gave some invisible sign and the gate opened.

As Robert Bellamy drove ahead, he saw a third cyclone fence ahead of him. My God, he thought, I'm in the Land of Oz.

Another uniformed guard walked up to the car. As Robert Bellamy reached for his wallet the guard looked at the licence plate and said, "Please drive straight ahead to the administration building, Commander. There will be someone there to meet you."

"Thank you."

The gate swung open and Robert followed the driveway up to an enormous white building. A man in civilian clothes was standing outside, waiting, shivering in the chill October air. "You can leave your car right there, Commander," he called out. "We'll take care of it."

Robert Bellamy left the keys in his car and stepped out. The man greeting him appeared to be in his thirties, tall, thin and sallow. He looked as though he had not seen the sun in years.

"I'm Harrison Keller. I'll escort you to General Hilliard's office."

They walked into a large high-ceilinged entrance hall. A man in civilian clothes was seated behind a desk. "Commander Bellamy ..."

Robert Bellamy swung around. He heard the click of a camera.

"Thank you, sir."

Robert Bellamy turned to Keller. "What ...?"

"This will take only a minute," Harrison Keller assured him.

Sixty seconds later, Robert Bellamy was handed a blue and white identification badge with his photograph on it.

"Please wear this at all times while you're in the building, Commander."

"Right."

They started walking down a long, white corridor. Robert Bellamy noticed security cameras mounted at twenty-foot intervals on both sides of the hall.

"How big is this building?"

"Just over two million square feet, Commander."

"What?"

"Yes. This corridor is the longest corridor in the world, nine hundred and eighty feet. We're completely self-contained here. We have a shopping centre, cafeteria, post exchange, eight snack bars, a hospital complete with operating room, a dentist's office, a branch of the State Bank of Laurel, a dry-cleaning shop, a shoe shop, a barber shop, and a few other odds and ends."

It's a home away from home, Robert thought. He found it oddly depressing.

They passed an enormous open area filled with a vast sea of computers. Robert stopped in amazement.

"Impressive, isn't it? That's just one of our computer rooms. The complex contains three billion dollars' worth of decoding machines and computers."

"How many people work in this place?"

"About sixteen thousand."

So what the hell do they need me for? Robert Bellamy wondered.

He was led into a private elevator that Keller operated with a key. They went up one floor and started on another trek down a long corridor until they reached a suite of offices at the end of the hall.

"Right in here, Commander." They entered a large reception office with four secretaries' desks. Two of the secretaries had already arrived for work. Harrison Keller nodded to one of them. She pressed a button and a door to the inner office clicked open.

"Go right in, please, gentlemen. The General is expecting you."

Harrison Keller said, "This way."

Robert Bellamy followed him into the inner sanctum. He found himself in a spacious office, the ceilings and walls heavily soundproofed. The room was comfortably furnished, filled with photographs and personal artifacts. It was obvious that the man behind the desk spent a lot of time there.

General Mark Hilliard, Deputy Director of NSA, appeared to be in his middle fifties, very tall, with a face carved in flint, icy, steely eyes, and a ramrod-straight posture. The General was dressed in a grey suit, white shirt and grey tie. I guessed right, Robert thought.

Harrison Keller said, "General Hilliard, this is Commander Bellamy."

"Thank you for dropping by, Commander."

As though it had been an invitation to some tea party.

The two men shook hands.

"Sit down. I'll bet you could do with a cup of coffee."

The man was a mind-reader. "Yes, sir."

"Harrison?"

"No, thank you." He took a chair in the corner.

A buzzer was pressed, the door opened and an oriental in a mess jacket entered with a tray of coffee and Danish pastry. Robert noted that he was not wearing an identification badge. Shame. The coffee was poured. It smelled wonderful.

"How do you take yours?" General Milliard asked.

"Black, please." The coffee tasted great.

The two men were seated in soft leather chairs facing each other.

"The Director asked that I meet with you."

The Director. Edward Sanderson. A legend in espionage circles. A brilliant, ruthless puppet-master, credited with masterminding dozens of daring coups all over the world. A man seldom seen in public and whispered about in private.

"How long have you been with the 17th District Naval Intelligence Group, Commander?" General Milliard asked.

Robert played it straight. "Fifteen years." He would have bet a month's pay that the General could have told him the time of day when he had joined ONI.

"Before that, I believe you commanded a naval air squadron in Vietnam."

"Yes, sir."

"You were shot down. They didn't expect you to pull through."

The doctor was saying, "Forget about him. He won't make it." He had wanted to die. The pain was unbearable. And then Susan was leaning over him. Open your eyes, sailor, you don't want to die. He had forced his eyes open and through the haze of pain was staring at the most beautiful woman he had ever seen. She had a soft oval face and thick black hair, sparkling brown eyes and a smile like a blessing. He had tried to speak, but it was too much of an effort.

General Hilliard was saying something.

Robert Bellamy brought his mind back to the present. "I beg your pardon, General?"

"We have a problem, Commander. We need your help."

"Yes, sir?"

The General stood up and began to pace. "What I'm about to tell you is extremely sensitive. It's above Top Secret."

"Yes, sir."

"Yesterday, in the Swiss Alps, a NATO weather balloon crashed. There were some experimental military objects aboard the balloon that are highly secret."

Robert found himself wondering where all this was leading.

"The Swiss government has removed those objects from the balloon, but, unfortunately, it seems that there were some witnesses to the crash. It is of vital importance that none of them talk to anyone about what they saw. It could provide valuable information to certain other countries. Do you follow me?"

"I think so, sir. You want me to speak to the witnesses and warn them not to discuss what they saw."

"Not exactly, Commander."

Then I don't under

"What I want you to do is simply track down those witnesses. Others will talk to them about the necessity for silence."

"I see. Are the witnesses all in Switzerland?"

General Milliard stopped in front of Robert. "That's our problem, Commander. You see, we have no idea where they are. Or who they are."

Robert thought he had missed something. "I beg your pardon?"

"The only information we have is that the witnesses were on a tour bus. They happened to be passing the scene when the weather balloon crashed near a little village called ..." He turned to Harrison Keller.

"Uetendorf."

The General turned back to Robert. "The passengers got off the bus for a few minutes to look at the crash and then continued on. When the tour ended, the passengers dispersed."

Robert said slowly, "General Hilliard, are you saying that there is no record of who these people are or where they went?"

"That is correct."

"And you want me to go over and find them?"

"Exactly. You've been very highly recommended. I'm told that you speak half a dozen languages fluently and you have an excellent field record. The Director arranged to have you temporarily transferred to NSA."

Terrific. "I assume I'll be working with the Swiss government on this?"

"No, you'll be working alone."

"Alone? But ..."

"We must not involve anyone else in this mission. I can't stress enough the importance of what was in that balloon, Commander. Time is of the essence. I want you to report your progress to me every day."

The General wrote a number on a card and handed it to Robert. "I can be reached through this number day or night. There's a plane waiting to fly you to Zurich. You'll be escorted to your apartment, so you can pack what you need, and then you'll be taken to the airport."

So much for "Thank you for dropping by". Robert was tempted to say, "Will someone feed my goldfish while I'm gone?" but he had a feeling the answer would be, "You have no goldfish."

"In your work with ONI, Commander, I assume you've acquired intelligence contacts abroad?"

"Yes, sir. I have quite a few friends who could be use ..."

"You're not to get in touch with any of them. You are not authorized to make any contacts at all. The witnesses you're looking for are undoubtedly nationals of various countries." The General turned to Keller. "Harrison ..."

Keller walked over to a filing cabinet in the corner and unlocked it. He removed a large manila envelope and passed it to Robert.

"There's fifty thousand dollars in here in different European currencies, and another twenty thousand in US dollars. You will also find several sets of false identifications that may come in handy."

General Hilliard held out a thick, shiny black plastic card with a white stripe on it. "Here's a credit card that ..."

"I doubt if I'll need that, General. The cash will be enough, and I have an ONI credit card."

"Take it."

"Very well." Robert examined the card. It was drawn on a bank he had never heard of. At the bottom of the card was a telephone number. "There's no name on the card," Robert said.

"It's the equivalent of a blank cheque. It requires no identification. Just have them call the telephone number on the card. It's very important that you keep it with you at all times."

"Right."

"And Commander?"

"Sir?"

"You must find those witnesses. Every one of them. I'll inform the Director that you have started the assignment."

The meeting was over.

Harrison Keller walked Robert to the outer office. A uniformed marine was seated there. He rose as the two men came in.

"This is Captain Dougherty. He'll take you to the airport. Good luck."

"Thanks."

The two men shook hands. Keller turned and walked back into General Hilliard's office.

"Are you ready, Commander?" Captain Dougherty asked.

"Yes." But ready for what? He had handled difficult intelligence assignments in the past, but never anything as crazy as this. He was expected to track down an unknown number of unknown witnesses from unknown countries. What are the odds against that? Robert wondered. I feel like the White Queen in Through the Looking-glass. "Why sometimes I've believed as many as six impossible things before breakfast." Well, this was all six of them.

"I have orders to take you directly to your apartment and then to Andrews Air Force Base," Captain Dougherty said. "There's a plane waiting to ..."

Robert shook his head. "I have to make a stop at my office first."

Dougherty hesitated. "Very well. I'll go there with you and wait for you."

It was as though they didn't trust him out of their sight. Because he knew that a weather balloon had crashed? It made no sense. He surrendered his badge at the reception desk, and walked outside, into the chill breaking dawn. His car was gone. In its place was a stretch limousine.

"Your car will be taken care of, Commander," Captain Dougherty informed him. "We'll ride in this."

There was a high-handedness about all this that Robert found vaguely disturbing.

"Fine," he said.

And they were on their way to the offices of Naval Intelligence. The pale morning sun was disappearing behind rain clouds. It was going to be a miserable day. In more ways than one, Robert thought.