“Well, that’s certainly a flattering beginning,” Chavasse said. “What’s the story?”

The Chief carefully inserted a Turkish cigarette into an elegent silver holder. “When were you last in Tibet, Paul?”

Chavasse frowned. “You know that as well as I do. Three years ago, when we brought out the Dalai Lama.”

“How would you feel about going in again?”

Chavasse shrugged. “My Tibetan is still pretty fair. Not fluent, but good enough. It’s the other problems specific to the area which would worry me most. Mainly the fact that I’m a European, I suppose.”

“But I understood you to say you’d helped out the Dalai Lama three years ago,” Professor Craig said.

Chavasse nodded. “But that was different. Straight in and out again within a few days. I don’t know how long I could get by if I was there for any period of time. I don’t know if you’re aware of this fact, Professor, but not a single Allied soldier escaped from a Chinese prison camp during the Korean War, and for obvious reasons. Drop me into Russia in suitable clothes and I could pass without question. In a street in Peking, I’d stick out like a sore thumb.”

“Fair enough,” the Chief said. “I appreciate your point, but what if we could get round it?”

“That would still leave the Chinese,” Chavasse told him. “They’ve really tightened up since I was last there. Especially after the Tibetan revolt. Although mind you, I think their control of large areas must be pretty nominal.” He hesitated and then went on, “This thing – is it important?”

The Chief nodded gravely. “Probably the biggest I’ve ever asked you to handle.”

“You’d better tell me about it.”

The Chief leaned back in his chair. “What would you say was the gravest international problem at the moment – the Bomb?”

Chavasse shook his head. “No, I don’t think so. Not anymore, anyway. Probably the space race.”

The Chief nodded. “I agree, and the fact that John Glenn and those who have followed him have successfully emulated Gagarin and Titov has got our Russian friends worried. The gap is narrowing – and they know it.”

“Is there anything they can do about it?” Chavasse said.

The Chief nodded. “Indeed there is, and they’ve been working on it for too damned long already – but perhaps Professor Craig would like to tell you about it. He’s the expert.”

Professor Craig took off his spectacles and started to polish their lenses with the handkerchief from his breast pocket. “The great problem is propulsion, Mr. Chavasse. Bigger and better rockets just aren’t the answer, not when it comes to travelling to the moon, and anything farther involves immense distances.”

“And presumably the Russians have got something?” Chavasse said.

Craig shook his head. “Not yet, but I think they may be very near it. Since 1956, they’ve been experimenting with an ionic rocket drive using energy emitted by stars as the motive force.”

“It sounds rather like something out of a science-fiction story,” Chavasse said.

“I only wish it were, young man,” Professor Craig said gravely. “Unfortunately it’s hard fact, and if we don’t come up with another answer quickly we might as well throw in the towel.”

“And presumably, there is another answer?” Chavasse said softly.

The professor adjusted his spectacles carefully and nodded. “In normal circumstances, I would have said no, but in view of certain information which has recently come into my hands, it would appear that there is still a chance for us.”

The Chief leaned forward. “Ten days ago, a young Tibetan nobleman arrived in Srinagar, the capital of Kashmir. Ferguson, our local man, took him in charge. Besides possessing valuable information about the state of things in western Tibet at the present time, he was also carrying a letter for Professor Craig. It was from Karl Hoffner.”

Chavasse frowned. “I’ve heard of him vaguely. Wasn’t he some kind of medical missionary in Tibet for years?”

The Chief nodded. “A very wonderful man whom most people have completely forgotten. Remarkably similar career to Albert Schweitzer. Doctor, musician, philosopher, mathematician. He’s given forty years of his life to Tibet.”

“And he’s still alive?” Chavasse said.

The Chief nodded. “Living in a small town called Changu about one hundred and fifty miles across the border from Kashmir. Under house arrest, as far as we can make out.”

“This letter,” Chavasse said, turning to Professor Craig. “Why was it addressed to you?”

“Karl Hoffner and I were fellow students and research workers for years.” Craig sighed heavily. “One of the great minds of the century, Mr. Chavasse. He could have had all the fame of an Einstein, but he chose to bury himself in a forgotten country.”

“But what was in the letter that was so interesting?” Chavasse asked.

“On the face of it, nothing very much. It was simply a letter from one old friend to another. He’d apparently heard that this young Tibetan was making a break for it and decided to take the opportunity of writing to me, probably for the last time. He’s in poor health.”

“How are they treating him?”

“Apparently quite well.” Craig shrugged. “He was always greatly loved by the people. Probably the Communists are using him as a sort of symbol. He said in his letter that he had been confined to his house for more than a year and to help pass the time had returned to his greatest love, mathematics.”

“Presumably this is important?”

“Karl Hoffner is probably one of the great mathematicians of all time,” Professor Craig said solemnly. “Do you mind if I get a little technical?”

“By all means,” Chavasse told him.

“I don’t know the extent of your knowledge of mathematical concepts,” Craig said, “but you are perhaps aware that Einstein demonstrated that matter is nothing but energy fixed in a rigid pattern?”

“E equals mc squared.” Chavasse grinned. “I’m with you so far.”

“In a celebrated thesis written for his doctorate while a young man,” Craig went on, “Karl Hoffner demonstrated that energy itself is space locked up in a certain pattern. His proof involved an audacious development of non-Euclidean geometry which was as revolutionary as Einstein’s theory of relativity.”

“Now, you’ve completely lost me,” Chavasse said.

“It doesn’t matter.” Craig smiled. “Probably only six brains on earth were capable of understanding his theory at the time, such was its complexity. It aroused considerable interest in academic circles and was then virtually forgotten. It was only theoretical, you see. It led nowhere and had no conceivable practical application.”

“And now he’s taken it one stage further,” Chavasse said. “Is that what you’re leading up to?”

Craig nodded. “He mentioned in his letter, quite casually I might add, that he had reached the solution to the problem. He has proved that space can be twisted, manipulated if you like, until it becomes an energy field.”

“And this is really important?” Chavasse said.

“Important?” The professor sighed. “For one thing, it relegates nuclear physics to roughly the Eocene Age of science. For another, it gives us an entirely new concept of space travel. We could produce an energy drive for our rockets from space itself, something that would be infinitely superior to the Russian concept of the ionic drive.”

“Do you think Hoffner has any idea of the important of his discovery?” Chavasse said.

Craig shook his head. “Given his circumstances, I don’t think he is even aware that orbital flights have taken place. If he knew that man had already crossed the space threshold, the value of his discovery would be at once obvious to him.”

“It’s incredible,” Chavasse said. “Quite incredible.”

“What’s even more to the point is that knowing this does us no damn good at all as long as the know-how remains locked in the brain of a sick old man under house arrest in a Communist-dominated country,” the Chief said. “We’ve got to get him out, Paul.”