was a puzzled frown on his face, lengthening the line made by
a scar which ran from his forehead down the side of his nose. The scar was
the result of a crash landing on Neptune.

"I don't get it, sir," he said. "A single plate from a rocket tube . . . So
what if it didn't oxidize?"

"That makes me feel much better." Carson smiled, an inner bitterness making
the smile wry. "I didn't get it either," he went on. "A mechanic named
Gomez got it; a foreman named Jacobs got it; a lab man named Britton got
it; but the chief of "Two Eyes" missed the boat. I feel swell about that."
He rose suddenly and hammered his fist on the desk. "Every one of us in
Intelligence ought to be cashiered!"

"Take it easy," Ben cautioned. "All because of that plate?"

Carson slumped back into his chair. "Yes. And because we have failed in our
duty. Our only hope is that we may have time to make it up. I'll give you
the facts:

"Those tubes are made of Virium, but even Virium develops scale. After next
week it will develop even more, because next week we make the changeover to
the new fuel. If Wayne had made his mistake two weeks later there would
have been so much deposit in the tubes that Gomez would not have noticed
the difference.

"Now, Virium is one of the most standardized products in the world. So
Gomez was rightly astonished that the tube didn't oxidize evenly. Jacobs
saw further. Virium is the toughest metal we know of; if this piece was
tougher it might be a discovery of major importance. So Britton analyzed
the plate."

"Now we get to the point," Sessions grinned.

Carson stabbed a finger at him. "Right. And the point is that this one
section of plate is not Virium! In fact, it is a substance which we are
positive does not exist in our system!"

"Wait a second. What do you mean by 'system'?"

"I mean every single bit of matter that lies between here and Ventura B."

"Maybe it's not a natural substance. Not an element."

"We thought of that. It's an element, and one we know nothing of."

"Do you mind if I sit down, sir?" Ben asked suddenly.

The enormity of the thing had struck him, almost dazzling him with its
implications. Carson laughed bitterly and waved him to a chair, then went
on talking.

"Precisely, Ben. The question is: How did this strange substance get into
the tube of an Interplanetary rocket called the Astra? To answer that we
checked on the ship. The Astra is one of the few ships which have ever gone
bey