Part 3

Linda nodded. "It's presence has been known, of course," she replied. "It leads to an underground cavern that stretches for miles under the surface. It's the burial place of the first dynasty Martians. But there are many such places below the Red Desert country. Always it has been thought they contained nothing of value."

They reached the bottom level and stood staring out before them. Where the floor of the desert above had been red in color, the surface here was ochre, a dull uncertain floor that gave off a radiance of its own and illuminated the underground cavern with a faint unreal glow. The grotto stretched in three directions as far as the light permitted them to see. At intervals of every twenty feet or so, large rectangular blocks, ten to fifteen feet high and twelve feet long, dotted the expanse. In a way the place looked like a vast apiary.

"Each one is a grave," Linda said quietly. "The block, of course, is only a marker. The crypt is lower down."

Jimmy scowled. "And one of those crypts contains the figurines, eh? Like looking for a needle in a haystack."

She gripped his arm. "We've got to find the right one before Garth. We've got to, do you understand! He's somewhere down here now, with those two hirelings of his. When--if--we do find it, this will destroy them." She pressed a short tube in Jimmy's hands.

Like three sleep-walkers, they paced slowly out among the stone blocks. And now Jimmy realized the proportions of the task they had set themselves to do. Each of the blocks was equipped with a vault-like door of massive weight and size, surrounded by a panel of those strange hieroglyphics, and with an intricate series of bizarre lock dials on its surface. The blocks looked exactly the same.

Above them in the dimness of the ceiling a heavy whirring sounded, and at intervals a curious bird-like creature with pointed wings and a weazened human face swooped down to be momentarily visible in the half light.

"_Sarkonivals_," Linda said shortly. "The early Martians were superstitious of them and transported them here to guard the burial grounds. They must feed on a variety of moss that grows down here."

They moved on. The rows of burial blocks seemed endless. Jimmy came to a halt.

"We're getting no place fast," he said. "Have you no clue at all as to which block it might be?"

Linda shook her head. Hanley was staring up above him, apparently fascinated by the strange flying creatures.

"You know," he said slowly, "I read about those _sarkonivals_ once. They always fly in groups of an even twenty, save when some atmospheric disturbance causes them to alter their formation."

He pointed upward. "They _are_ all in groups of twenty except over that block over there. Above that they seem to be in confusion."

Jimmy followed his gaze and frowned thoughtfully. He paced forward to the block in question, stood there watching the movements of the _sarkonivals_.

Suddenly he turned to Linda. "Look. See how their flying formation is always the same? They're twenty of them up there all right, and they start to circle the block in a compact mass. But as soon as they strike a point directly above it, they separate. First five, then three, then two, six, one, and three. Always the same order. Do you suppose that might be the combination? A magnetic disturbance issuing from the block in such a way as to prevent the usual twenty-formation and break it up in that fashion?"

"Jimmy!" Her eyes lighted. "I think you've got it!"

He seized the ancient combination wheel, put his strength to it. Slowly, a fraction of an inch at a time, it began to turn. Jimmy hesitated.

"I can't read these numerals, if they are numerals," he said. "I don't know where to start."

Linda studied the markings. "I think that's the symbol for absolute zero," she said. "Try it anyway."

He began to turn the wheel again, counting off the numbers as he watched the irregular formation of _sarkonivals_ above him. "Five, three, two, six, one, three."

Twice he tried with no result. The third time there was a dull whirring somewhere in the bowels of the block, and the door slowly swung open. Within, a short passageway ended at another door, equipped with another series of dials.

Here Jimmy nodded in satisfaction. "I should be able to crack this."

He opened his carry-case, took out the headphones and slipped them on. Linda and Hanley pressed close, watching him.

"Hurry," the girl said. "I don't like it here."

A voice behind answered her.

"No need to hurry, Mr. Starr, alias the Nebula. Just take your time, but be sure you open it."

* * * * *

They wheeled. Three figures blocked the passage. In the lead, leaning comfortably against the side wall, stood Hamilton Garth, a heat gun leveled before him. Behind him were the two pseudo-I.P. men.

"Very nice of you to save us the trouble of locating the figurine cache," Garth said smoothly. "Now all you have to do is open that inner door and then help us carry a load of the images back to our tracto-car. You have nothing to worry about. If you obey orders, no harm will come to you. If you don't, well, don't forget I have a nice ace-in-the-hole. I have only to tell the world that James C. Starr, president of Triplanetary Shipping is the much-wanted cracksman, the Nebula."

Jimmy, Linda, and Hanley looked at each other.

"Come," said Garth. "This place oppresses me as much as it does you. Get to work."

Silently Jimmy adjusted the headphones again and began to move the dials. Five minutes passed. Then he stood back, grasped the handle and pulled the door open.

The interior was black, but a click of the torch revealed row upon row of Thro-Pahl images. There were hundreds here, and there must be hundreds more in the lower crypt.

And then Jimmy remembered the metal tube Linda had given him when they first entered this underground chamber. He drew forth the tube and with a quick motion threw it before him.

Nothing! The crypt remained steeped in silence.

"What was that you threw?" demanded Garth. "Answer, damn you!"

Jimmy shrugged. "It was a tube of setro-frenalot--NSK 54," he said. "I think you know what that means, Mr. Garth. The double detonation explosive. If it doesn't explode upon the first impact, the slightest jar, the slightest whisper of sound will discharge it."

Garth's face went black with rage. "You damned double-crossing--!"

He tossed his heat gun to one of the two pseudo-I.P. men and plunged into the vault. Halfway the significance of Jimmy's words came home to him. Gingerly, a step at a time, he began to work his way toward the metal tube that lay in the light of his electric torch.

Now he stood directly above it. He reached down, let his fingers fasten about the tube. With the greatest of care, he lifted it and began to catwalk back to the door of the vault.

But at the threshold Jimmy uttered a cry of alarm and swept Linda protectingly into his arms.

"What's the matter?" Garth demanded.

"The calibo-marset fire. Blue flame. It's started in the setro-frenalot. It's going to go off."

Garth's eyes shot wide with fear. He looked down at the tube in his hands, then abruptly swung and hurled it through the open doorway into the vault.

There was a low roar, mounting to a crescendo report. A cloud of smoke belched outward, and the ground beneath their feet trembled. At the first indication of Garth's action, Jimmy, Linda, and Hanley had hurled themselves backward, away from the vault door. Garth too had whirled and leaped like a released spring to safety.

But the two I.P. men were caught. They had not heard Jimmy's exclamation--hadn't time to guess what was coming. An avalanche of rubble and huge stones washed forward to sweep relentlessly over them. An instant later only a sound of dust-rising debris and masonry fragments marked the spot where they had stood.

As the deafening reverberations rolled back into silence, Hamilton Garth seemed to grasp the significance of the situation like a man in a dream. For a moment he stood there, rigid, eyes narrowing, lips quivering. Then with a snarl of profanity, he charged straight at Jimmy Starr.

Jimmy's head was still reeling dizzily from a blow dealt him by a flying chunk of rock, and he saw the onrushing Trust man through a haze. Garth's fist bludgeoned into his jaw. Another blow drove into his midsection, sent a wave of nausea sweeping through him. And then a picture of his father lying helpless on the study floor shot into his mind's eye; with it came a sudden realization of all that the _superiors_ class--Garth's class--stood for. He snapped his fists forward and began to hit with all the strength he possessed at the face before him. He was still flailing his arms in and out, when Hanley stepped in and pulled him back.

* * * * *

It was the following morning, and the tracto-car was speeding smoothly down Canal Grand. In the driver's seat sat Jimmy Starr, a bandage on his temple, a smile on his face.

Beside him was Linda Hall, and in the rear tonneau Phil Hanley held a heat gun to cover the bound figure of Hamilton Garth.

"We did it," Jimmy said at length. "The figurine cache is destroyed forever."

The girl nodded.

"And the canal project won't be abandoned either," Jimmy continued. "That explosion opened up a shaft leading to a still lower crypt where there's enough pure _pxar_ ingots stored to build all the canal locks the engineers need. Pure _pxar_. Not the figurine kind."

Linda nodded again.

"What I want to know is this," she said. "I know that that tube you threw into the vault didn't go off the first time because the detonator-cap didn't hit. But what kind of explosive is setro-frenalot? I never heard of it.

"Neither did I," Jimmy laughed. "It goes back to the juke box age of the twentieth century. In other words, double talk."