He reflected, and his frown deepened.

“If I didn’t know what I know, I might.  So if I land on emergency rockets the blueskins down below may decide that I come from Weald.  And in that case it would be reasonable to blast me before I could land and unload some fighting men.  On the other hand, no ship from Weald would conceivably land without impassioned assurance that it was safe.  It would drop bombs.”  He turned to the girl.  “How many Darians down below?”

She shook her head.

“You don’t know,” said Calhoun, “or won’t tell, yet.  But they ought to be told about the arrival of that ship at Weald, and what Weald thinks about it!  My guess is that you came to tell them.  It isn’t likely that Dara gets news directly from Weald.  Where were you put ashore from Dara, when you set out to be a spy?”

Her lips parted to speak, but she compressed them tightly.  She shook her head again.

“It must have been plenty far away,” said Calhoun restlessly.  “Your people would have built a ship, and made fine forged papers for it, and they’d travel so far from this part of space that when they landed nobody would think of Dara.  They’d use make-up to cover the blue spots, but maybe it was so far away that blueskins had never been heard of!”

Her face looked pinched, but she did not reply.

“Then they’d land half a dozen of you, with a supply of make-up for the blue patches.  And you’d separate, and take ships that went various roundabout ways, and arrive on Weald one by one, to see what could be done there to—­” He stopped.  “When did you find out positively that there wasn’t any plague any more?”

She began to grow pale.

“I’m not a mind reader,” said Calhoun.  “But it adds up.  You’re from Dara.  You’ve been on Weald.  It’s practically certain that there are other ... agents, if you like that word better, on Weald.  And there hasn’t been a plague on Weald so you people aren’t carriers of it.  But you knew it in advance, I think.  How’d you learn?  Did a ship in some sort of trouble land there, on Dara?”

“Y—­yes,” said the girl.  “We wouldn’t let it go again.  But the people didn’t catch—­they didn’t die.  They lived—­”

She stopped short.

“It’s not fair to trap me!” she cried passionately.  “It’s not fair!”

“I’ll stop,” said Calhoun.

He turned to the control board.  The Med Ship was only planetary diameters from Orede, now, and the electron telescope showed shining stars in leisurely motion across its screen.  Then a huge, gibbous shining shape appeared, and there were irregular patches of that muddy color which is seabottom, and varicolored areas which were plains and forests.  Also there were mountains.  Calhoun steadied the image, and squinted at it.

“The mine,” he observed, “was found by members of a hunting party, killing wild cattle for sport.”

Even a small planet has many millions of square miles of surface, and a single human installation on a whole world will not be easy to find by random search.  But there were clues to this one.  Men hunting for sport would not choose a tropic nor an arctic climate to hunt in.  So if they found a mineral deposit, it would have been in a temperate zone.