"They've spotted us!" I called. "Open fire-only a mile to go now!"

I heard Aethelbert and Ben's curt acknowledgments, felt the tremors in the rock that meant their heavy guns were firing. Another alien unit hurtled into view and opened fire.

On my left, Ben whooped suddenly, "I slipped home to him, Cap'n. Old Aethelbert was keepin' him busy, and I took him low. Watch!"

I saw the leading pursuer veer to the right, bound up a low slope, and smash headlong into a towering rock slab. There was a shock that lifted me clear of the ground, slammed me ahead; a fountain of molten chromalloy and rock leaped up, fell all around; then dust closed over the scene.

The pass was ahead now; I swung to enter it, gunned up the long slope. Ben followed, trailing by a quarter-mile. Far back, Aethelbert was coming up fast, the fire of the remaining alien unit lighting his defensive screens.

I reached the crest of the pass, came to a halt looking down on a vast complex of works-tunnel heads, squat sheds, low circular structures of unknown function-gray, rough-textured, stark and ugly against the bleakness of the lunar landscape. And beyond the warren of buildings, a tower reached up into the glittering black of the night sky, a ragged shape like a lone spire remaining from a fallen ringwall: the Place That Must Be Defended.

I looked back down the trail. From my vantage point I could see the broad sweep of the plain: the distant jumble of rock where we had regrouped, the milling mass of the enemy, strung out in a long pincers that enveloped the tiny group of winking lights that was Thomas and his dwindling band; and nearer, the dust trail reaching almost to the foot of the pass, and the second trail, close behind.

From halfway down the sloping trail, Ben called, "Aethelbert's in trouble; he's taken a hit, I think-and that fellow's closing on him. I better give him a leg up."

"Aethelbert!" I called. "Are you all right?"

There was no answer. I saw him slow as he entered the pass, then turn sideways, blocking the entry, his guns pointed toward the enemy. The oncoming unit poured fire into the now stationary target; it rocked to hit after hit. Ben, coming up beside me, swung his guns, opened fire on the alien unit as it came within range.

"Aethelbert, we'll cover you!" I called. "Come on up into the pass; you'll have shelter there!"

"I'll tarry here, Jones," came a faint reply. "There'll be no lack of foes to tempt my thunder."

"Just a few yards farther!"

"Bare is the back without brother behind it," he sang out. "Now take the mead-hall of the goblins by storm, and may Odin guide your sword-arm!"

"I'm goin' back for him!" Ben yelled.

"As you were, Ben! The target's ahead! Let's go and get it!" I launched myself down the slope without waiting to see him comply. A moment later, he passed me, racing to run interference.

"Head for the tower," I called. The first buildings were close now-unlovely constructions of featureless stone, puny in scale. I saw a tiny dark shape appear in a tunnel mouth, saw it bound toward a cluster of huts-and recognized it as one of the dog-things, looking no larger to me than a leaping rat, its head grotesquely muffled in a breathing mask-apparently its only protection from the lunar vacuum. I veered, bore down on it, saw its skull-face twist toward me as my treads caught it, pulped it in an instant, flung the bristled rag that was its corpse far behind.

Ben braked to a halt before a wide gate, swung his forward battery on it, blasted it to rubble, then roared ahead through the gap, with me close behind A shock wave struck me like a solid wall of steel. I felt myself go up, leap back, crash to the rocky ground, slide to rest in a shower of debris. Half dazed, I stared through the settling dust, saw the blackened hulk that had been my Confederate scout, smoke boiling from every aperture, his treads gone, gun barrels melted. I shouted his name, caught a faint reply:

"Cap'n… don't move… trap… all automatic stuff. I saw 'em… too late. Hellbores… set in the walls. You'll trigger 'em… when you move… don't… stir…" I felt his mind-field fade, wink out.

I scanned the interior of the compound, saw the black mouths of the mighty guns, aimed full on me-waiting. I reached out, felt for the dim glow of cybernetic controls, but found nothing. They were mechanically operated, set to blast anything that moved in the target area. The detonation that had halted me in my tracks had saved my life.

Ben was dead. Behind me, Aethelbert held the pass alone, and on the plain, my comrades fought on, in ever-dwindling numbers, covering my desperate bid for victory.

And I was here, caught like a fly in a web-helpless, fifty yards from my objective.

Chapter Sixteen

The explosion had blackened the pavement of the court, gouged a crater a yard deep, charred the blank invulnerable walls that ringed it. My hull, too, must be blackened and pitted. I could see fragments of my blasted comrade scattered all across the yard; splashes of molten metal were bright against the drab masonry.

There were openings in the walls, I noted as the last of the dust fell back, and the final shreds of black smoke dissipated in the near-vacuum. They seemed no bigger than ratholes, but I realized they were actually about a yard wide and half again as high.

As I watched, a pale snout poked from one; then the lean withers and flanks of a demon appeared, its size diminished by contrast with my immense body. The thing wore a respirator helmet like the one I had seen earlier; straps crisscrossed its back. It bounded lightly to the burned-out hulk of Ben's body. It circled, stepping daintily around chunks that still glowed red. It came across to me, then disappeared as it passed under the range of my visual sensors.

I held myself motionless, carefully withdrew vitality from my external circuitry, closed myself behind an inner shield of no-thought. Alone in the absolute darkness of sensory deprivation, I waited for what might happen next.

Faintly, I felt a probing touch-ghostly fingers of alien thought that groped along my dark circuits, seeking indications of activity. There was an abortive shudder as an impulse was directed at my drive controls. Then the probe withdrew.

Cautiously, I extended sensitivity to my visual complex, saw the creature as it trotted back to its hole. Again the compound was silent and empty, except for the corpse of the great machine that had been my friend.

Quickly, I ran an inspection, and discovered the worst: my drive mechanism was fused at vital points in the front suspension, and my forward batteries were inoperative-warped by the terrific heat of the blast from the hellbores that had smashed Ben. I was trapped inside ten thousand terrestrial tons of inert, dead metal.

More demons emerged from the building, trotting from the same arched doorway. Other creatures followed-squat, many-armed things like land-walking octopi. They went to Ben, swarmed over the hot metal. Perched high on the blackened carapace, they set to work. Below on the dusty ground, the demons paced, or stood in pairs, silently watching.

I considered reaching out to touch a demon mind, and rejected the idea. I was not skilled enough to be sure of not alerting it, warning it that something still lived inside my scorched and battered hull.

Instead, I selected a small horror squatting on the fused mass that had been Ben's forward turret; I reached out, found the awareness-center…

Grays and blacks and whites, dimly seen, but with distorted pseudoscent images sharp-etched; furtive thoughts of food and warmth and rest; a wanderlust, and a burning drive for a formless concept that was a female…

It was the brain of a cat, installed in the maintenance machine, its natural drives perverted to the uses of the aliens. I explored the tiny brain, and saw the wonderful complexity of even this simple mechanism-vastly more sophisticated than even the most complex of cybernetic circuits.