For two hundred and seventy years America had been totally cut off from the rest of the world by an impenetrable wall of raging atomic fury. To the frightened countries of the Old World, what had once been the greatest of all powers was now the most fearful of all mysteries. No man ached to know what lay behind that frightful barrier more than Emmett O'Hara, restless air-sentinel of the International Patrol-whose American ancestors had been stranded in Britain the day the Atom Curtain was raised. Then, on December 20, in the year 2230, while on routine patrol, O'Hara did the impossible. He broke through the barrier-and lived! But the full story of O'Hara's discoveries and adventures in Atomic America is so utterly breath-taking that readers are sure to rate it a classic of modern science-fiction.