The three boys scrambled down the side of the hill and found the cave
Tom had seen. After a quick search Astro found a boulder that
half-covered the front of the cave, and the three boys pushed it close
to the entrance.

"Go on. Get inside now," said Astro. "I'll push this one into position
and then pile a few smaller ones on top and around it. That way you'll
be able to get air and still be hidden."

Tom and Roger crawled into the hole and settled themselves as Astro
pushed the boulder up against the opening. He piled the other stones
around it quickly. When he had just about finished he heard someone
behind him. He turned and saw one of the colonists scrambling down the
side of the hill, heading for him.

"Here they come," Astro whispered hoarsely. "Spaceman's luck!" He
dropped the last stone in place and turned to face the man who was now
almost upon him.

Tom and Roger crouched in the darkness and listened intently.

"You there!" they heard the colonist cry. "Halt! Don't move or I'll
freeze you!"

Astro stood still. The man came up to him and felt the cadet's uniform
for a hidden weapon. Then he jammed the ray gun into Astro's back and
ordered him down the hill. Astro started walking, hardly daring to
breathe, but suddenly the man stopped.

"Where are the others?" he demanded.