"Surely he told you, Admiral? Just a doctor attached to the Navy to carry out — "

"A naval doctor?"

"Well, not exactly. I — "

"A civilian?"

I nodded, and the admiral and Swanson exchanged looks that they were at no pains at all to conceal from me. If they were happy at the prospect of having aboard America's latest and most secret submarine a man who was not only a foreigner but a civilian to boot, they were hiding it well. Admiral Garvie said: "Well, go on."

"That's all. I carry out environmental health studies for the services. How men react to extremes of environmental conditions, such as in the Arctic or the tropics, how they react to conditions of weightlessness in simulated space flight or to extremes of pressure when having to escape from submarines. Mainly — "

"Submarines." Admiral Garvie pounced on the word. "You have been to sea in submarines, Dr. Carpenter? Really sailed in them, I mean?"

"I had to. We found that simulated tank escapes were no substitute for the real thing."

The admiral and Swanson looked unhappier than ever. A foreigner — bad. A foreign civilian — worse. But a foreign civilian with at least a working knowledge of submarines — terrible. I didn't have to be beaten over the head to see their point of view. I would have felt just as unhappy in their shoes.

"What's your interest in Drift Ice Station Zebra, Dr. Carpenter?" Admiral Garvie asked bluntly. -

"The Admiralty asked me to go there, sir."

"So I gather, so I gather," Garvie said wearily. "Admiral Hewson made that quite plain to me already. Why you, Carpenter?"

"I have some knowledge of the Arctic, sir. I'm supposed to be an expert on the medical treatment of men subjected to prolonged exposure, frostbite and gangrene. I might be able to save lives or limbs that your own doctor aboard might not."

"I could have half a dozen such experts here in a few hours," Garvie said evenly. "Regular officers of the U. S. Navy, at that. That's not enough, Carpenter."

This was becoming difficult. I tried again. I said, "I know Drift Station Zebra. I helped select the site. I helped establish the camp. The commandant, a Major Halliwell, has been my closest friend for many years." The last was only half the truth, but I felt that this was neither the time nor the place for overelaboration.

"Well, well," Garvie said thoughtfully. "And you still claim you're just an ordinary doctor?"

"My duties are flexible, sir."

"I'll say they are. Well, then, Carpenter, if you're just a common garden-variety sawbones, how do you explain this?" He picked up a signal form from the table and handed it to me. "This has just arrived in reply to Commander Swanson's radioed query to Washington about you."

I looked at the signal. It read: "Dr. Neil Carpenter bona fide beyond question. He may be taken into your fullest, repeat, fullest confidence. He is to be extended every facility and all aid short of actually endangering the safety of your submarine and the lives of your crew." It was signed by the Chief of Naval Operations.

"Very civil of the Chief of Naval Operations, I must say." I handed back the telegram. "With a character reference like this, what are you worrying about? That ought to satisfy anyone."

"It doesn't satisfy me," Garvie said heavily. "The ultimate responsibility for the safety of the «Dolphin» is mine. This message more or less gives you carte blanche to behave as you like, to ask Commander Swanson to act in ways that might be contrary to his better judgment. I can't have that."

"Does it matter what you can or can't have? You have your orders. Why don't you obey them?"

He didn't hit me. He didn't even bat an eyelid. He wasn't activated by pique about the fact that he wasn't privy to the reason for the seeming mystery of my presence there; he was genuinely concerned about the safety of the submarine. He said: "If I think it more important that the «Dolphin» should remain on an active war footing rather than go haring off on a wildgoose chase to the Arctic, or if I think you constitute a danger to the submarine, I can countermand the C.N.O.'s orders. I'm the Commander-in-Chief on the spot. And I'm not satisfied."

This was damnably awkward. He meant every word he said, and he didn't look the type who would give a hoot for the consequences if he believed himself to be in the right. I looked at both men, looked at them slowly and speculatively, the unmistakable gaze, I hoped, of a man who was weighing others in the balance; what I was really doing was thinking up a suitable story that would satisfy both. After I had given enough time to my weighing-up — and my thinking — I dropped my voice a few decibels and said: "Is that door sound-proof?"

"More or less," Swanson said. He'd lowered his own voice to match mine.

"I won't insult either of you by swearing you to secrecy or any such rubbish," I said quietly. "I want to put on record the fact that what I am about to tell you I am telling you under duress, under Admiral Garvie's threat to refuse me transport if I don't comply with his wishes."

"There will be no repercussions," Garvie said.

"How do you know? Not that it matters now. Well, gentlemen, the facts are these. Drift Ice Station Zebra is officially classed as an Air Ministry meteorological station. Well, it belongs to the Air Ministry, all right, but there's not more than a couple of qualified meteorologists among its entire personnel."

Admiral Garvie refilled the glass and passed it to me without a word, without a flicker of change in his expression. The old boy certainly knew how to play it cool.

"What you will find there," I went on, "are some of the most highly skilled men in the world in the fields of radar, radio, infrared, and electronic computers, operating the most advanced instruments ever used in those fields. We know now, never mind how, the count-down succession of signals the Russians use in the last minute before launching a missile. There's a huge dish aerial in Zebra that can pick up and amplify any such signals within seconds of its beginning. Then long-range radar and infrared home-in on that bearing and within three minutes of the rocket's lift-off they have its height, speed, and course pinpointed to an infinitesimal degree of error. The computers do this, of course. One minute later the information is in the hands of all the antimissile stations between Alaska and Greenland. One minute more and solidfuel infrared homing antimissile rockets are on their way: then the enemy missiles will be intercepted and harmlessly destroyed while still high over the Arctic regions. If you look at a map, you will see that in its present position Drift Ice Station Zebra is sitting practically on Russia's missile doorstep. It's hundreds of miles in advance of the present DEW line — the 'distant early warning' system. Anyway, it renders the DEW line obsolete."

"I'm only the office boy around those parts," Garvie said quietly. "I've never heard of any of this before."

I wasn't surprised. I'd never heard any of it myself, either, not until I'd just thought it up a moment ago. Commander Swanson's reactions, if and when we ever got to Drift Station Zebra, were going to be very interesting. But I'd cross that bridge when I came to it. At present, my only concern was to get there.

"Outside the drift station itself," I said, "I doubt if a dozen people in the world know what goes on there. But now you know. And you can appreciate how vitally important it is to the free world that this base be maintained in bein amp; If anything has happened to it, we want to find out just as quickly as possible «what» has happened so that we can get it operating again."

"I still maintain that you're not an ordinary doctor," Garvie smiled. "Commander Swanson, how soon can you get under way?" — -

"Finish loading the torpedoes, move alongside the «Hunley»load some final food stores, pick up extra Arctic clothing, and that's it, sir."