Alexander Blish was the security chief at Tomloy's, the new nuclear physics research centre. They were doing things in the plant that had never been done before. They were tapping power sources so terrible that their ultimate conclusions could be heaven on earth or a hell of destruction. Armageddon might be just around the dangerous corner which humanity called tomorrow.

Blish had problems. There were alien forces to consider. There were human traitors who were prepared to sell out the Empire if the price was right. The price could be as high as planetary control.

Wilkie Gordon was Alexander's second problem. Wilkie was an outworlder with strange wild talents. He could be an invaluable ally or a deadly enemy. Blish had to decide and decide at once. If he made the wrong choice there was just a chance that Gordon could detect the aliens and renegades before they reached the J-Pile...