He strode tensely up and down, smacking his fist into his palm. "The lever!" he exclaimed. "That lever! It's our only answer! If we could get to it.... But how can we? We couldn't break into the dome, now the Rogans are on the watch for us, with anything less than a charge of explosives. Or a tank. G.o.d, how I'd like to have an old-fashioned, fifty-ton army tank here now!"

Greca exclaimed aloud as Brand's fleeting mental picture of one of Earth's unwieldy, long-discarded war tanks registered on her brain.

"There is the great beast there," she said hesitantly, pointing a slim forefinger at the huge lizard that had backed into a far corner and was regarding them out of dull, savage eyes. Then she shook her head.

"But that is impossible. Impossible!"

The men stared at her, with dawning realization in their minds. Then they gazed at each other.

"Of course," said Brand. "Of course! Greca, you're marvelous! Wish we had a tank? Why, we've got one! A four-legged mountain of meat that ought to be able to plow through the side of that dome like a battering ram through cardboard!"

"But it's not possible," replied Greca, her head dropping dejectedly.

"My people, as driven slaves, till the fields with great animals that were trapped in the surrounding jungles. They harness other great animals to haul burdens. But none of the beasts are like _this_ one.

This kind cannot be tamed or harnessed. It is too ferocious. It is used only as a scourge of fear, to crush us into complete submission."

"Can't be tamed?" Brand said. "We'll see about that! Come on, Dex."

"Just a minute," said Dex. He flattened against the wall, motioning them to do the same. Then he leveled his tube at the door.

Slowly, cautiously, the door began to swing back; and the Rogan that Dex had heard fumbling with the bolt stuck his huge head out to locate the escaped prisoners.

Dex pressed the release coil of his tube. Without a sound, the Rogan slumped to the ground, a smoking cavity in its shoulders at the spot where its head had been set. In an instant the body, too, disappeared; an upward coiling wisp of black smoke marking its vanishing.

Another Rogan, tiptoeing out, met the same fate; and another. And then the door was banged shut again, and the bolt ground into place on the inside.

"That'll teach 'em to be careful how they try to rush us from _that_ door," said Dex, through set teeth. "Now let's see if that tank scheme of ours can be worked."

He picked up a tube dropped by one of the Rogans, and handed it to Brand; showing him which coil to press to get full force, as Greca had in turn informed him.

"Down the field," commanded Brand. "We'll go about thirty yards apart, and try to herd this brute back through the walls of the dome building. Once it's inside, we'll try to rush to the lever before the Rogans can down us, and jam the thing past its terminal peg and into reverse action. I don't know that there _is_ a reverse to it--but we can try.

"Greca dear,"--the girl started at the warmth of his thought, and a faint pink rose to her pale cheeks--"you'd better stay by my side.

Your place as hostage-priestess of your people wouldn't save you if those devils catch you now. Besides, you can keep your tube leveled at the doorway as we go, and discourage any Rogans who might pluck up courage to try coming out again."

They started down the field toward the nightmare thing that snarled and hissed in its corner. On one side of the big enclosure walked Brand, with Greca close beside him, glancing continuously over her shoulder at the rear door, and holding her tube in readiness to check any charge the Rogans might attempt to make from the tower building.

On the other side, keeping an equal pace, advanced Dex.

With tubes of death as whips, and with death for themselves set as the stake for which they gambled, they went about their attempt to drive the brainless monster before them through the solid wall of the dome building. And there followed what was probably the strangest animal act the universe has ever witnessed.

The first thing to do was to rout the enormous lizard out of the corner where sullen fear had sent it squatting. Dex contrived to do that by standing next to the wall at its side, and sending a searing ray that just touched the scaly, tremendously thick hide. The monster bellowed deafeningly, and, with a spot smoking on its flank, waddled sideways to the center of the field. Its head and swaying long neck faced the Earthmen and its back was against the wall of the dome building. To that extent, at least, they had the creature placed; but they soon found that the struggle had only just begun.

Brand got far enough around to focus his tube on the tip of the huge tail, in an effort to swing the gigantic thing about. There was an unearthly shriek from the colossal beast, and a foot and a half of its tail disappeared.

"Careful," called Dex, his jaw set and grim as the monster lashed out in its wrath. "If you bore in too long with that tube there'll be nothing left of our tank but a cloud of smoke."

Brand nodded, wordlessly, walking on the b.a.l.l.s of his feet like a boxer, holding himself ready to swerve the thing should it charge them. Which--next instant--it did!

With a whistling bellow it gathered its tons of weight and thundered with incredible quickness at the gnats that were stinging its flanks and tail.

Desperately Brand played the tube across the vast chest, scoring a smouldering gash in the scale-covered flesh just above the gash Dex had seared a few moments before.

"Sorry, old fellow," Brand muttered to the screaming beast. "We hate to bait you like this, but it has to be done. Come on, now, through that wall behind you, and give us a chance at the lever."

But through the wall behind it the vast creature, not unnaturally, refused to go! It darted from side to side. Backward and forward. Up to the wall, only to back bewilderedly away from it. And constantly the tubes flicked their blistering, maddening rays along its monstrous sides and tail, as the Earthmen tried to guide it into the wall.

"Hope there's enough left of it to do the trick," said Brand, white-lipped. The monster was smoking in a dozen spots now, and several of the hump-like scales on its back had been burned away till the vast spine looked like a giant saw that was missing a third of its teeth. "G.o.d, I'm thinking we'll kill it before we can drive it through that wall!"

Greca nodded soberly, keeping her eyes on the distant door to their rear. Twice that door had been opened, and twice she had directed the death rays into its opening to mow down the gangling figures behind it. But she had said nothing of this to her man. He was busy enough with his own task!

"The door to the dome--" Dex shouted suddenly.

But Brand merely nodded, even as a discharge from his tube annihilated the Rogan that had appeared in the doorway before them. He had seen that door stealthily opening even before Dex had.

"It had better be soon, Dex!" he called. "Rogans in front of us--Rogans behind us--and--look out! On your side of the fence, there!"

Dex whirled in time to pick off a grotesque, pipe-like figure that had suddenly appeared on the broad wall of the enclosure. Then he turned to the frenzied problem of driving the monster through the building wall.

"The thing's going mad, Brand!" he cried, his voice high-pitched and brittle. "Watch out!"

It was only too evident that his statement was true. The baited monster, harried blindly this way and that, hounded against the blank wall behind it by something that bit chunks of living flesh out of its legs and sides, was losing whatever instinctive mental balance it had ever had. Its dimly functioning brain, probably no larger than a walnut in that gigantic skull, ceased more and more to guide it.

With a rasping scream that set the Earthmen's teeth on edge, it charged for the wall on Dex's side. Dex just managed to swerve it with a blast from the tube so prolonged that half its great lower jaw fell away.

At this the t.i.tanic thing went wholly, colossally mad! It whirled toward Brand, jerking around again as a searing on that side jarred its dull sensory nerves, then headed at last straight toward the stone wall of the dome building.

With the rays from both tubes flicking it like monstrous spurs, it charged insanely toward the bulge of the circular wall. With all its tons and tons of weight it crashed against the stonework. There was a thunderous crackling noise, and the wall sagged in perceptibly, while the metal roof bent to accommodate the new curvature of its supporting beams.

The monstrous lizard, jerked off its huge legs by the impact, staggered up and retreated toward the two men. But again the maddening pain in its hindquarters sent it careening toward the building wall.

This time it raised high up on its hind legs in a blind effort to climb over it. "G.o.d, it must be five stories tall!" e.j.a.c.u.l.a.t.ed Brand.

Thunderingly its forelegs came down on the edge of the roof.

There was another deafening crash of stone and shrieking of torn metal. Just under the cornice, the wall sagged away from the roof and the top rows of heavy stone blocks slithered inward.

"Again!" shouted Brand.

His tube was pointing almost continuously now at the metal door leading from the dome building. The Rogans inside, at the shocks that were battering down a section of their great building, were all trying to get out to the yard at once. In a stream they rushed for the doorway. And in loathsome heaps they fell at the impact of the ray and shriveled to nothingness on the bombarded threshold.

"Once more--" Brand repeated, his voice hoa.r.s.e and tense.