"I think we'll find them, sir. Or Commander Swanson will."

"What makes you so sure?" he asked slowly. "Hunch?"

"You could call it that."

He laid down his glass and his eyes were no longer twinkling. "Admiral Hewson was most evasive about you, I must say. Who are you, Carpenter? «What» are you?"

"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.