the
gold-mines there. He's planning to obliterate the Earth. We've got to
go in like mad dogs and shoot to kill. No matter if we kill every
living thing there, even our own people who are inmates of the Moon's
penal settlement, we've got to account for Axelson."

"Yes, Sir."

"We can't guess how he got those gold-ships that returned with neon
and argon for the Moon colonists. But he mustn't get us. Let the men
understand that. That's all."

"Very good, Sir."

The teleradio suddenly began to splutter: A-A-A, it called. And
instantly every sound ceased about the landing-stage. For that was the
call of Axelson, somewhere upon the Moon.

"Axelson speaking. At the next full moon all the American Province of
the World Federation will be annihilated, as the Chinese Province was
at the last. There's no hope for you, good people. Send out your
vacuum liners. I can use a few more of them. Within six months your
world will be depopulated, unless you flash me the signal of
surrender."

Would the proud old Earth have to come to that? Daily those ominous
threats had been repeated, until popular fears had become frenzy. And
Nat was being sent out as a last hope. If he failed, there would be
nothing but surrender to this man, armed with a super-force that
enabled him to lay waste the Earth from the Moon.

Within one hour, those invisible, death-dealing rays had destroyed
everything that inhaled oxygen and exhaled carbon. The ray with which
the liner was equipped was a mere toy in comparison. It would kill at
no more than 500 miles, and its action was quite different.

As a prelude to Earth's surrender, Axelson demanded that World
President Stark and a score of other dignitaries should depart for
the Moon as hostages. Every ray fortress in the world was to be
dismantled, every treasury was to send its gold to be piled up in a
great pyramid on the New York landing-stage. The Earth was to
acknowledge Axelson as its supreme master.

* * * * *

The iron claws were turning with a screwlike motion, extending
themselves, and slowly raising the interplanetary vessel until she
looked like a great metal fish with metal legs ending with suckerlike
disks. But already she was floating free as the softly purring engines
held her in equipoise. Nat climbed the short ladder that led to her
deck. Brent came up to him again.

"That teleradio message from Axelson--" he began.

"Yes?" Nat snapped out.

"I d