For a mile they followed the trail. Then Paula had left the sand for a bare ledge of age-worn volcanic rock. The wind had erased what traces she might have left here. They skirted the edge of the ledge, but no prints were visible in the sand. The small red eye of the sun was just above the ocherous western rim of the planet. Their perspiring bodies shivered under the first chill of the frozen Martian night.
"It's no use," Bill muttered, sitting down on a block of time-worn granite, and wiping the red mud from his face. "She's probably been gone for hours. No chance."
"I've got to find her!" the Prince cried, his lean, red-stained face tense with determination. "I'll circle about a little, and see if I can't pick up the trail."
Bill sat on the rock. He looked back at the low dark rim of cliffs, a mile behind, grim and forbidding against the somber, indigo sky. The crimson, melancholy splendor of the Martian sunset was fading in the west.
The silver sunship was out of sight behind the cliffs. But he could see the little blue globes, like spinning moons of sapphire, circling watchfully above it. They were lower now, some of them not a thousand feet above the hidden sunship.
Abruptly, one of them was enveloped in a vivid flare of orange light. Its blue gleam flickering out, and it fell in fragments of twisted white metal. Bill knew that it had been struck with a rocket torpedo.
The reply was quick and terrible. Slender, dazzling shafts of incandescent whiteness stabbed down toward the ship, each of them driving before it a tiny bright spark of purple fire, coruscating, iridescent.
They were the atomic bombs, Bill knew. A dozen of them must have been fired, from as many ships. In a few seconds he heard the reports of their explosions—in the thin, still air, they were mere sharp cracks, like pistol reports. They exploded below the line of his vision. No more torpedoes were fired from the unseen sunship. Bill could see nothing of it; but he was sure that it had been destroyed.
He heard the Prince's shout, thin and high in the rare atmosphere. It came from a hundred yards beyond him.
"I've found the trail."