"Well?"
"What you don't know," Halsey said, "is that Grantline expects to find radiactum on the Moon."
We gasped.
"Exactly," said Halsey. "The ill-fated Ballon Expedition thought they had found it on the Moon, shortly after its merit was discovered. A new type of ore—a lode of it is there somewhere, without doubt."
He added vehemently, "Do you understand now why we should be suspicious of this George Prince? He has a criminal record. He has a thorough technical knowledge of radium ores. He associates with Martians of bad reputation. A large Martian company has recently developed a radiactum engine to compete with our Earth motor. There is very little radiactum available on Mars, and our government will not allow our own supply to be exported. What do you suppose that company on Mars would pay for a few tons of richly radioactive radiactum such as Grantline may have found on the Moon?"
"But," I objected, "That is a reputable Martian company. It's backed by the government of the Martian Union. The government of Mars would not dare—"
"Of course not!" Captain Carter exclaimed sardonically. "Not openly! But if Martian Brigands had a supply of radiactum I don't imagine where it came from would make much difference. The Martian company would buy it, and you know that as well as I do!"
Halsey added, "And George Prince, my agents inform me, seems to know that Grantline is on the Moon. Put it all together, lads. Little sparks show the hidden current.
"More than that: George Prince knows that we have arranged to have the Planetara stop at the Moon and bring back Grantline's ore.... This is your last voyage this year. You'll hear from Grantline this time, we're convinced. He'll probably give you the signal as you pass the Moon on your way out. Coming back, you'll stop at the Moon and transport whatever radiactum ore Grantline has ready. The Grantline Flyer is too small for ore transportation."
Halsey's voice turned grimly sarcastic. "Doesn't it seem queer that George Prince and a few of his Martian friends happen to be listed as passengers for this voyage?"