"I turned back south. The MR count was dropping instantly. It didn't make sense. It was not possible, because I'd been between the Pole and the Curtain when I had blacked out. It was then that I made an automatic check on my position. Latitude 73--I'd gotten far off course during the time I'd been blacked out. Longitude 136--I checked that again. But that was it. The longitude was 136 degrees." O'Hara knew exactly where that position placed him. But he did precisely what any laboratory technician would have done--he repeated his experiment, trying to find an error in his calculations. There was none and he knew it. He knew, even before that final check, that he had got through the Atomic Curtain. Somehow, he had got past the wall of death that had cut off the Western Hemisphere for almost two hundred and seventy years. He now was flying above the ice field that abutted the upper reaches of the North American continent. He glanced at his fuel gauge, and then turning south he set his motors at their maximum cruising speed. If he was trapped within the Western Hemisphere, the terra incognita that had fascinated him since he was old enough to read, he knew that he must fly as far below the desolation of the Arctic as his craft would go. And then-- "Then we shall see," O'Hara told himself. "Yes, we shall see--at last." PART TWO When he at last convinced himself that he had got through the Atomic Curtain, O'Hara said, his first feeling was a wild and utterly unreasoning elation. "I've done it!" he kept repeating to himself, much as if he had booted home a twenty-to-one shot at the races at Aintree. "I've actually done it--the first man in two hundred and seventy years to smash through. Now we shall see!" But that exuberance did not long continue. For here he was, presumably in the Western Hemisphere, the cradle of the future, a terra incognita since that Third World War, and it seemed no different from the polar regions that he had been flying for the International Patrol. No different at all--the limitless gray reaches of the sky, the same vast twisted sheets of polar ice pierced only at great intervals by craggy, barren peaks--the islands of the Beaufort Sea, above the northern coast of Canada.