I nodded. "And suppose they do accept Jean for what she claims to be, a potential deserter, what then?"

"Her original orders were to identify the route and the lay-over station, as well as the people involved, as far as possible. Then she was to extricate herself by any available means, and report. No other action was required of her."

"I'd say it was plenty, sir."

"Yes. Unfortunately, I have had to modify those orders in the light of new information." He hesitated, then he drew a piece of paper towards him, took the ball-point desk pen out of its holder and printed a single word. He replaced the pen and pushed the paper across the desk towards me, turning it so that I could read what he had written. "Do you know what that word means, Eric?"

I looked at the paper. The word, printed in capital letters, was AUDAP. It meant nothing to me. "No, sir. They play so many games with the alphabet around here, I've given up trying to figure them out."

Mac took back the piece of paper and drew an ash-stand closer. He burned the paper carefully, powdered the ashes, and tripped the trap to let them fall into the base of the stand.

"That word," he said, "represents one of the most highly classified secrets in Washington, and you've never seen it, of course."

"Of course."

"It's very, very secret," he said. "Only we and the Russians know about it, nobody else."

"I see."

"They do not, however, know as much as they would like. Do you know anything about submarines, Eric?"

"Yes, sir. They travel under water."

"Until recently this was not strictly true," Mac said. "Until recently, a submarine was a surface vessel capable of submerging for short periods of time. Even so, it was a potent naval weapon. Why?"

"I suppose, because when it's submerged, you can't see it."

"Precisely. And with the advent of, first the snorkel, and then nuclear power, enabling the boats to go under water and stay there, this advantage has increased tremendously. Radar doesn't work under water. Sonar is relatively short range and unreliable; besides, the instrument has to be in the water to be effective. This makes it impractical for use from fast search airplanes; the only way large sea areas can be efficiently patrolled." He looked at me across the desk, like a teacher in a classroom. "Do you know which weapon of ours the Russians fear most?"

I shrugged. "The big bombers, I suppose, sir. Or the Atlas missiles with nuclear warheads."

"If they haven't found some kind of an answer to bombers yet, after all the time they've had to work at it, they're not as smart as I think. And the big intercontinental ballistic missiles still have to be fired from fixed sites which can be located by intelligence work-we don't make it very difficult-and more or less neutralized by other missiles or by sabotage. No, the weapon they really fear is the weapon they can't neutralize because they can't find it. It is the weapon we operate out of Holy Loch, Scotland: the Polaris submarine." Mac got up and walked to the window and spoke without looking around. "Of course, what I have told you is the Navy version. An Army or Air Force man might give a different picture. Still, the admiral who explained the situation to me was most persuasive."

"Yes, sir."

"Each Polaris submarine carries sixteen Polaris missiles," Mac said, regarding the sunny view outside. "At present the range is about a thousand miles, but it is being extended. We have-the exact number is confidential- say, half-a-dozen of these submarines operational, but more are being built. Even the half-dozen already on patrol in northern waters give the man in the Kremlin a great deal to think about at night, I should imagine. Six times sixteen is ninety-six nuclear missiles, waiting invisibly under the ocean within range of his major cities. The submarines don't even have to surface to shoot. There's nothing he can do about them-unless he can locate them first." He paused. "The word I wrote down for you, AUDAP, stands for a little gadget just invented known as an Airborne Underwater Detection Apparatus."

There was a short silence. Mac swung from the window and returned to his chair and sat down facing me. He put the tips of his fingers together delicately, and looked at them.

"We don't know," he said, "the mind of the opposition. We don't know how close they are to taking the big gamble. We do know that, even discounting Navy enthusiasm, the Polaris submarine must be a powerful deterrent. But if they should get their hands on a device that gave them some hope of neutralizing that deterrent-" I shrugged expressively.

"Have they?"

"No," Mac said. "The device is safe. The plans are safe. However, the man who invented the device and drew up the plans has disappeared, a gentleman named Dr. Norman Michaelis."

"I see." I frowned thoughtfully. "Was he kidnapped or did he go under his own power?"

"He was on vacation, resting up from his labors on AUDAP. He disappeared while sailing alone on the Bay in a small boat. The wind dropped towards evening, as it does. Some people in a power boat offered him a tow, but he refused it, saying he'd work his way in under sail. Well after dark, the friends with whom he was staying went out in a motor cruiser to see how he was making out. They found the boat sailing merrily along on the evening breeze with no one on board."

"The fact that he refused a tow might indicate something."

"If you don't know sailors," Mac said, "it might. However, a real sailboat man-as Michaelis seems to be

– would rather spend all night trying to get home on a whisper of breeze, rather than be snatched into port at the end of a towline."

"I'll take your word for it," I said. "This nautical kick is out of my line."

"The details don't matter, and the question of whether or not Michaelis absconded voluntarily is also quite irrelevant. Whatever he knows, he can be made to tell, you know that. If they once get him over there, and their experts get to work on him with the latest drugs and interrogation techniques, he will talk freely whether he wants to or not. They all do. It must not be allowed to happen. That is why we-you-have to take such drastic means to bring matters to a head where Jean is concerned. We have to sell them on her, very quickly. If we have luck, and Michaelis and she are held for the same shipment- apparently they don't ship very often, which improves our chances. But they have to be persuaded to take her soon, while he is still within reach."

"This is getting to be quite an order our girl is being handed. Now, not only does she have to fool these people, learn all about them and their organization, whatever it is, and make her getaway, she's got to escape with a helpless Ph.D on her back."

"Dr. Michaelis isn't quite helpless. As a matter of fact, he's well under fifty, athletic, and considered handsome in some quarters."

"Sure. They're all personality kids, these days, and in a tough spot I'd trade them all for one ugly old-timer with store teeth or no teeth at all."

Mac said, as if there had been no interruption, "And I am not ordering Jean to escape with Dr. Michaelis, even if she does have the good fortune to reach him."

I looked at him. "I'm kind of slow, sir. You have to bring me along by easy stages."

"If she can rescue him, that will be fine," Mac said quietly, "but as you point out, it could well turn out to be an impossible task."

"So?"

"Jean's orders are quite simple and specific," Mac said. "You may as well know what they are; they apply to you if by some remote chance you should find yourself in a position to carry them out." He looked at me over the desk. "Our instructions specify only that the knowledge in Dr. Michaelis' head must not leave the country," he said deliberately. "How to achieve this result is left entirely to the discretion of the agent on the spot. No questions will be asked. Do you understand?"