Like the scout, Stuart had studied the route in advance, but traversing it in the dark was a grimly different matter. The double shadows of the two moons were confusing and made him stumble. Once a sensitive bush of some kind shuddered and drew back with a moan when he grasped it for support. He shuddered and brushed sweat off his face and sleeve. What did anyone know, after all, about the number of dangerous organisms this planet harbored? Carnivorous plants, for instance, or even animals, might not have sense enough to avoid iron complexes such as human blood.... Something soft beneath his foot shrieked horribly in the night and slid away. He went down on one knee, but waved when Brettner turned as if to help him up. "I'm letting this get me," he thought angrily. He got up and jogged along again, trying to imitate the scout's powerful stride. Abruptly they came upon the trail. They had just started along it when a warning came from the _Special Agent_. "One of those animals on the prairie must have picked up your scent. Probably a hell-cat sloping off toward the trail now. Ye gods! ... he must be doing sixty kilometers! Now he's slowing ... you should see him about a hundred meters ahead in a few seconds. He's sneaking onto the trail." The linguist's heart thudded as he crouched in shadow with the scout. "What do we do, Brettner?" he whispered. "Have to use this," the other replied, hauling out a wide-barrelled, clumsy looking Texas Slugger. "Picked up this sweetheart on Callisto, but I only got three shells." He aimed down the path through an offset sight. "Don't get behind this, laddie." * * * * * In the moonlight farther up the trail, a sinuous beast like a huge armor-plated cat glided out from the brush. It opened jaws a meter wide, showing double rows of dull green phosphorescent teeth, and began to lope toward the men. The scout fired when it was less than sixty meters away, and a rocket-propelled projectile hissed out toward it. A few meters out, the 2000-G drive of the projectile cut in, and the missile crashed into the hell-cat with terrible impact. The creature was a hollow mass of pulp almost instantaneously. The only sounds had been the brief hiss of the rocket, the even shorter crackling of the accelerated drive, and an earth-shuddering crunch when the device had struck a wall of rock beyond the beast. Apparently these had not alarmed the other nocturnal creatures about, for the various animal cries went on as before. "Come on," said the scout, resuming the trail. "We got to hurry." Stuart followed, wrinkling his nose at the horrible stench of the dead animal. Nearby, a brightly glowing hole in the rock showed where the missile had buried itself and disintegrated.