"We made the detour like you said," he whispered. "Fighting our way over rocks, around craters. Tough going. About three miles from here our half-circle brought us back to the trail. All okay. Miller was ahead of me by maybe a hundred yards. We kept our guns in our hands, and a sharp lookout. Then ... then ... all of a sudden I heard Miller yelling in my earphones. He was hopping up and down ... straight up and down, half-crazy with fright.... Just as I was running toward him, he told me to stay back, that he was trapped. Trapped!" Harris choked. "He could hop up and down all right, but he couldn't move in the horizontal! Nothing around him, nothing to be seen anywhere, but he could only move one way! Up and down! It ain't human, I tell you! Ain't natural! How...."
"Miller could move only in the vertical?" Joan echoed. "But ... but ... no comprehensible force on earth...."
"This ain't earth, miss," Harris muttered. "And Miller's out there, three miles up the trail, trapped...."
Grant reached for his space-suit. "Come on!" he exclaimed. "We're going out! Harris, you'll stay here with Miss Conway...."
"No!" The girl shook her head, eyes like gray steel. "I'm in command of this expedition ... and I'm going along! Danger or no danger! I got you men into this mess, and I'm going to help you get out!"
"Sorry." Grant shook his head. "I admire your courage, but we're up against something unknown, something dangerous. You'd be more of a hindrance than a help. Call me old-fashioned, romantic, anything you please, but you're staying here. Harris, I'll be responsible for any charges of insubordination. See that she stays here. We're going to rescue Miller."
Lips pale, head high, the girl watched them clamber into their space-suits. Her pride, Grant realized, was cut deeply at having the command of the expedition thus taken from her. But this was no time for pride with Miller trapped by some mysterious force. Motioning to the others to follow, Grant sprang into the airlock.
Leaving the ship, the six men raced at top speed along the trail. Around crevasses and craters, past insanely sculptured rocks, through narrow passes. When they reached the spot where Kennerly's body had been found, Grant suddenly paused, staring. The patch of hoar-frost had been scraped away, a small hole perhaps a foot deep was exposed. Something previously buried in the ground had been removed! Grant shook his head. A bizarre, fantastic idea was beginning to take form in his mind. In a temperature close to absolute zero....
"Come on!" he exclaimed. "We've got to reach Miller! Hurry!"