The paper had been written about two years ago by Professor Roland Phillips, a peaceable Oxford cosmologist with no interest in politics. He had submitted it to the Royal Astronomical Society, and it was now becoming a little difficult to give him a satisfactory explanation of the delay in publication. Unfortunately—and this was the fact that caused great distress to Central Intelligence—Professor Phillips had innocently sent copies to his colleagues on Mars and Venus. Desperate attempts had been made to intercept them, but in vain. By now, the Federation must know that the Moon was not as impoverished a world as had been believed for two hundred years.

There was no way of calling back knowledge that had leaked out, but there were other things about the Moon which it was now equally important that the Federation should not learn. Yet somehow it was learning them; somehow, information was leaking across space from Earth to Moon, and then out to the planets.

When there’s a leak in the house, thought Sadler, you send for the plumber. But how do you deal with a leak which you can’t see—and which may be anywhere on the surface of a world as large as Africa?

He still knew very little about the scope, size and methods of Central Intelligence—and still resented, futile though that was, the way in which his private life had been disrupted. By training, he was precisely what he pretended to be—an accountant. Six months ago, for reasons which had not been explained and which he probably never would discover, he had been interviewed and offered an unspecified job. His acceptance was quite voluntary; it was merely made clear to him that he had better not refuse. Since then he had spent most of his time under hypnosis, being pumped full of the most various kinds of information and living a monastic life in an obscure corner of Canada. (At least, he thought it was Canada, but it might equally well have been Greenland or Siberia.) Now he was here on the Moon, a minor pawn in a game of interplanetary chess. He would be very glad when the whole frustrating experience was over. It seemed quite incredible to him that anyone would ever voluntarily become a secret agent. Only very immature and unbalanced individuals could get any satisfaction from such frankly uncivilized behavior.