Dwornrecognized it for an aircraft taking off.
Then he had to snatch for a handhold as the spider-machine lunged into adead run. At full speed on the level ground, it could make good time;the ground outside skimmed past at fifty or sixty miles an hour.
Qanya had spied some rocky outcroppings, which might furnish a modicumof shelter, about a mile away and some distance from the brink of thecliffs, and she was heading for them. But the terrain nearer at hand wasimplacably flat--and the enemy was airborne, a vicious winged shapegrowing at terrifying speed. Its whistling roar swelled and grewdeafening.
Qanya shouted something inaudible and pointed. Dworn understood, and,holding on for dear life in the pitching cabin, clawed his way withinreach of the fire-controls. Wrestling with the unfamiliar mechanism, hefought to train the spider's guns on the hurtling attacker.
Puffs of smoke bloomed high in air--but any hit on such a fast-movingtarget, from so unstable a platform, would have been a miracle. Theenemy screeched overhead, and an instant later flame and thunder eruptedall around the running spider. The machine stumbled and for a momentseemed going down, but it righted itself and staggered on.
Dworn shook his ringing head and saw the flier banking steeply half amile away, while a second and a third were climbing against the sky,gaining altitude to dive.
They couldn't last another thirty seconds, couldn't even hope to reachthe doubtful cover of the rocks.... Up ahead, two hundred yards, was alow mound, only a few feet high, the only nearby elevation of any sort.And it was plainly artificial, though wind-piled sand had softened itsoutlines; others like it were scattered around the periphery of thegreat sink, and Dworn guessed their nature as he saw a column of thealuminum crawlers beginning to emerge from the side of the one justahead. It must be the other end of a tunnel such as they had discoveredamong the cliffs....
He nudged Qanya urgently, shouted, "Head for that!"
She gave him a fleeting, wide-eyed look. The mound's low swell couldfurnish no shelter for the towering spider, and the tunnel mouth was ofcourse much too small to enter. But she veered without slackening speedin the direction indicated.
Dworn abandoned the useless guns. The mound, with a gleaming line ofcrawlers still parading out of it, swept closer; and at the same timethe desert echoed back the screaming onrush of the two new attackers.
Dworn wrenched open the cabin door with one hand. His other arm circledQanya's waist, dragged her away from the controls. She cried inuncomprehending shock as he swung her before him into the open doorway.They swayed there, high above the speeding ground, wind whipping at themas the spider pounded blindly on.
The mound loomed immediately at hand. Dworn prayed that he had judgedthe moment right, and with a mighty leap launched both of them out intospace.
A pistoning steel leg barely missed them. Even as they fell, the air wastorn by explosions as the swooping fliers opened fire.
* * * * *
Dworn hit the ground with almost stunning force. His hold on the girlwas broken and he was rolled helplessly over and over by his ownmomentum. But he fetched up on hands and knees, bruised and breathlessbut unhurt.
From the corner of his eye he saw Qanya sitting up dizzily, half-buriedin the drifted sand that had broken their fall. Apparently she too wasuninjured, but she was staring in horrified fascination after herrunaway machine.
The spider careened onward, no hand at its controls. It hit the line ofcrawling little machines coming from underground; it knocked onespinning end over end, and stepped squarely on another, stamping itflat. It recovered its balance amazingly, and loped on, even though oneleg was buckling beneath it--
Then it was hit dead-on by what must have been at least a hundred-poundhigh explosive rocket.
The winged killers shot low overhead with an exultant whoop of jets,peeling off to right and left of the column of smoke that rose andtowered where the spider had been struck. Out of the cloud, metalfragments soared glinting upward and arced back to earth, and on theground, amid smoke and dust, a metal limb was briefly visible, flexingconvulsively and growing still.
Dworn heard a smothered sound beside him. A tear rolled down Qanya'ssmudged cheek, and Dworn thought fuzzily, _Even spiders can cry_._Only_, he corrected, _she's not a spider any more she's now just aghost like me_.
If he hadn't been a ghost already, if he hadn't lost his ownmachine--the idea of jumping clear and saving both their human liveswhile letting the spider be destroyed would never have occurred to him.
He came to himself, hissed, "Down! Keep low and maybe they'll overlookus!"
They huddled together on the slope of the sandhill, while the victoriousflying enemy circled round in a miles-wide sweep and began descendingtoward their base again, wing-flaps braking them for landing.
And on the ground meanwhile, the crawlers which had come from the tunnelwere proceeding on their way, leaving two of their number behind withstrange indifference to their own casualties.
"What'll we do?" quavered Qanya.
Dworn had time to take stock of the situation. The tunnel-mound was, ashe had seen before, the only cover--and that a poor one--for aconsiderable distance. It was all of a quarter mile to the edge beyondwhich the cliffs fell away.
He tried to sound hopeful--whether for Qanya's sake or to keep up hisown courage, he could hardly have said. "I think we'll have to stayhere, and hope we're not noticed, until it gets dark. Then, maybe--"
Qanya caught her breath sharply and gripped his arm. "Look--there!"
Still far away across the sloping floor of the great bowl, but rapidlyapproaching from its center, moved a dust cloud. Beneath it, theexpiring sunlight glinted on the aluminum shells of at least a score ofthe ground machines.
Dworn said grimly, "Might have expected it; they'll be coming to lookover the scene of action and pick up the pieces. We've one chance; keepout of sight behind this little hill, and maybe they won't investigatetoo closely."
Qanya nodded, biting her lip. She could reckon as well as he how muchthat chance was worth.
* * * * *
The buzzing motors came nearer. The two cowering in the lee of themound, almost without daring to breathe, heard them halt, slow to idlingspeed one by one a little way off, where the wrecked spider lay. Fromthat spot obscure sounds began rising, thuds and gratings and a shrillhissing noise.
But then--the whine of a single high-speed engine rose again, clear totheir hearing. One of the enemy was approaching around the flank of thesandhill.
They crouched motionless, frozen. No hope in either flight or fight; onthe open ground, they would be run down in no time, and they had noweapons--even the notion of a weapon, as something apart from thefighting machine that carried it, was alien to their thinking.
The enemy vehicle rolled into full view and nosed slowly along the baseof the mound; its motor whining questingly, only a few yards of gentleslope between it and the huddled pair. Its vision-ports glinted redly inthe sunset glow, and Dworn could almost feel the raking of murderouseyes from behind them.... Like the other machines of this kind he hadseen it was small and without armor--it couldn't weigh more than acouple of thousand pounds, and it carried no guns. From the vantage ofhis armed and armored beetle, he had regarded its like as flimsy andharmless-looking.... But now he realized for the first time how helplessa mere human was against such a thing, and, with an irrepressibleshudder, how easily the grappling and cutting-tools this one wasequipped with might be employed for--dismantling--flesh and blood.
The machine paused momentarily. Then its engine revved up again. Itrolled on past, giving no sign of excitement, and vanished beyond thehillside.
"Dworn, Dworn, it didn't see us!" Qanya was sobbing with relief.
Dworn was staring after the enemy, brows puzzledly drawn downward. Thesounds from the other side of the mound went on uninterrupted--a clangorof metal, the prolonged shrilling of a cutting-torch, where evidentlythey were at work breaking up the smashed spider-
vehicle.
He said huskily, "Something's very queer about them.... Wait. I've _got_to take a look."
Qanya glanced at him in quick alarm as he started wriggling to the crestof the sandhill. Then she followed silently, and peered over the topbeside him.
Twilight was descending, but they could still see easily enough whatwent on out there. Not a hundred yards away, the little machines swarmedabout the spider, bringing their various wrecking equipment into play todismantle it rapidly under the watchers' eyes. Torches flared, winchestugged at fragments of the shattered monster. An aluminum cylinder witha serrated alligator snout rolled triumphantly away, bearing aloft theshank of a great steel leg....
But Dworn's attention was riveted by what was happening closer at hand.Here, near the tunnel-entrance that opened just below their observationpoint, lay the two crawlers which the runaway spider had disabled. Oneof these, the one which had merely been overturned and