hed them emerge out of the ammonia mist,
ray gun held tightly in his hand. Tom climbed into the air lock safely
and dropped the box on the edge of the platform, slumping to the deck
beside it. Astro followed seconds later, and then Miles.

"Don't stop now," barked Miles. "Put those boxes below with the rest of
them."

Tom got up slowly, leaning heavily on the outer edge of the
precariously placed box. The box suddenly tilted and then slipped out of
the air lock to disappear in the mist.

"Why, you clumsy--" Brett roared, raising his gun menacingly.

Astro stepped in front of Tom. "I'll get it," he cried. "Don't shoot!"

"Go on then," snarled Brett. "Go down with him, Miles. I'll stay here
with Corbett."

"You go down with him," sneered Miles. "I've been up and down that
ladder fifty times while you sat up here doing nothing."

"Is that so?" cried Brett angrily, turning to face the black-clad
spaceman. This gave Tom the opportunity he was waiting for. He pulled
the small charge of explosives from his tunic and held it in front of
him.

"All right, you two!" he shouted. "Drop those paralo-ray guns. This is
the booby trap you planted in the tunnel. You fire those ray guns and we
all go up together."

Brett jumped back. Miles took a half step forward and stopped. "You
haven't got the nerve," he sneered.

"Shoot and you'll find out," said Tom. "Go ahead! Shoot, if you've got
the guts. Get down the ladder, Astro," he said. "They won't fire as long
as I've got this in my hand."

Brett had begun to shake with fear but Miles brought his ray gun up
slowly. He aimed it at Astro who was starting down the ladder, his head
and shoulders still showing in the open air-lock portal. Tom saw what
Miles was going to do. "Jump, Astro!" he shouted.

Astro jumped at the exact instant Miles fired. "Rush him," cried Miles.
Brett made a headlong dash for Tom, but the cadet side-stepped at the
last moment and Brett fell headlong out of the ship, wailing in sudden
terror as he fell to the ground.

Miles turned to Tom. He ripped off his mask and with his free hand
closed the air-lock portal.

"You fooled Brett, but you didn't fool me, Corbett." He laughed. "It
takes a direct electric charge to set that stuff off. You just helped me
get rid of a very obnoxious partner." He leveled his paralo-ray gun.

"I hate to do this," he said, "but it's you or me."

He fired. Tom was again frozen into that immobile state more dead than
alive