"Thirty-eight," said Carter.

"There are thirty-eight people listed for the flight to Ferrok-Shahn
to-night," Halsey said slowly. "And some may not be what they seem." He
raised his thin dark hand. "We have information--" He paused. "I
confess, we know almost nothing--hardly more than enough to alarm us."

Captain Carter interjected, "I want you and Dean to be on your guard.
Once on the Planetara it is difficult for us to talk openly, but be
watchful. I will arrange for us to be doubly armed."

Vague, perturbing words! Halsey said, "They tell me George Prince is
listed for the voyage. I am suggesting, Haljan, that you keep your
eye especially upon him. Your duties on the Planetara leave you
comparatively free, don't they?"

"Yes," I agreed. With the first and second officers on duty, and the
captain aboard, my routine was more or less that of an understudy.

I said, "George Prince! Who is he?"

"A mechanical engineer," said Halsey. "An under-official of the
Earth Federated Radium Corporation. But he associates with bad
companions--particularly Martians."

I had never heard of this George Prince, though I was familiar with the
Federated Radium Corporation, of course. A semi-government trust, which
controlled virtually the entire Earth supply of radium.

"He was in the Automotive Department," Carter put in. "You've heard of
the Federated Radium Motor?"

* * * * *

We had, of course. A recent Earth invention which promised to
revolutionize the automotive industry. An engine of a new type, using
radium as its fuel.

Snap demanded, "What in the stars has this got to do with Johnny
Grantline?"

"Much," said Halsey quietly, "or perhaps nothing. But George Prince some
years ago mixed in rather unethical transactions. We had him in custody
once. He is known now as unusually friendly with several Martians in New
York of bad reputation."

"Well--" began Snap.

"What you don't know," Halsey went on quietly, "is that Grantline
expects to find radium on the Moon."

We gasped.

"Exactly," said Halsey. "The ill-fated Ballon Expedition thought they
had found it on the Moon some years ago. A new type of ore, as rich in
radium as our gold-bearing sands are rich in gold. Ballon's first
samples gave uranium atoms with a fair representation of ionium and
thorium. A richly radio-active ore. A lode of the pure radium is there
somewhere, without doubt."

* * * *