we couldn't get out of this cell — not with the door bolted by a wave-lock.'
'I've an idea that might get us out!” Thorn said feverishly. “It's a chance — our only one!'
'Try it, Gunner!” urged Sual Av,’ wide awake now.
With no hope in his face, Gunner Welk obeyed. He rocked back and forth in his chair until it tipped forward, his head coming down against Thorn's lap. Hitching painfully sidewise, the big Mercurian got his teeth into one of Thorn's leather arm-straps.
They heard his jaws working as he bit into the tough Jovian leather. Their psychophones continued to drone on, uttering their varying thoughts. But the rumble of the raging storm above was loud enough to keep the guards in the corridor from hearing.
Thorn felt the strap Gunner was chewing weaken. He tensed his arm in a fierce effort. The strap broke!
Quickly, Thorn unbuckled the other straps that held him. He tipped Gunner's chair back to normal position. Then he reached around and with numbed fingers found the tiny, needle-like electrode at the back of his skull, and gently pulled it out. He felt his scalp close over the minute incision. His psychophone went silent.
Thorn got to his feet. He staggered, his numbed limbs buckling under him at first. Then he steadied, and unbuckled the straps that held Sual Av and the Mercurian to their chairs.
'Don't disconnect your psychophones yet!” he warned them. “If the guards outside happened to notice that all our psychophones were dead, they'd suspect something at once.'
'Now what?” Sual Av whispered. “How can we get out of this cell without a wave-key to operate the lock?'
'Yes, what's your idea?” Gunner asked hoarsely.
'It came to me as I watched them changing spools in the psychophones tonight,” Thorn muttered. “I shut my mind off it till after they'd gone, so they wouldn't hear.'
He was taking down from its mounting the psychophone that for so many days had blared his thoughts. With quivering fingers, he began dissembling the intricate little machine. Tubes and coils and condensers came from it, as he rapidly took it apart.
'There are enough parts here,” he muttered feverishly. “If I can just remember enough of my tech-school training.'
Thorn began putting certain parts of the mechanism back together again, in a totally different hook-up. The tiny atomic generator that furnished power, the transformers and rectifiers — and then he worked long upon rewiring an “alternator,” connecting it electrically to a master modulator tube.
An hour passed, and another. The hubbub of storm was even louder from above. The droning of the other two Planeteers’ psychophones was almost inaudible through the roar.
Thorn finally straightened, holding the compact rebuilt mechanism in trembling hands. His face was dripping.
,'Now for it!” he whispered shakily to the other two Planeteers. He advanced with the little machine to the locked door.
'You've rebuilt the psychophone parts into a wave-projector?” Sual Av whispered, staring. “To use as a wave-key?'
'It won't work,” Gunner muttered. “It may project waves, but you don't know the secret frequency that will operate this lock. It might be any one of countless possible frequencies.'
But Thorn only nodded.
'I thought of that!” he said hoarsely. “I built an automatic modulator into the thing. It will start projecting waves of frequency down in the sixteenth octave, and run up to the forty-fifth, by steps of twenty vibrations each. You know all wave-locks are keyed in those octaves, for above them you get heat radiations.'
'It might work,” Sual Av agreed. “Most locks have an error-margin of ten vibrations per second, so your automatic step-ups ought to overlap all frequencies in those octaves.'
Thorn was already at the door. He held the end of his little makeshift projector against the inertrum door just inside the wave-lock. He was counting on the high power of his vibrations to penetrate the inertrum from inside, and reach the lock.
The little projector hummed as he touched its switch. Invisible waves were shooting from it into the lock, changing frequency by 20-vibration jumps each fraction of a second.
In a moment came a click from the wave-lock! The bolt had drawn back, as the right frequency released the lock.
'By heaven, it worked!” Gunner Welk exclaimed hoarsely, his eyes lighting with wild hope now.
Thorn peered tautly out through the door-grating. The two SP guards on duty were standing a few yards down the corridor, evidently discussing the storm that roared above.
Gunner and Sual Av now removed the needlelike electrodes of the psychophones from the tiny incisions, at the back of their skulls. They staggered stiffly from the chairs to Thorn's side, as he gently opened the unlocked door.
One of the SP men, seeing the cell door open from the corner of his eye, yelled and reached for his atom- pistol.
'Get them!” Thorn shouted hoarsely, lunging out.
The charging Planeteers reached the two Saturnians before they could level the weapons they had drawn. Thorn grabbed the atom-pistol of one of the green men, and twisted fiercely.
The Saturnian suddenly let go of the gun and jumped back, clawing a pocket-audio from his jacket. He shouted wildly into the little instrument.
'Dungeon-guards calling for help! The prisoners are—'
Thorn brought the atom-pistol down on the man's head, and he sank with a groan. Gunner and Sual Av had already knocked out the other guard, and the Mercurian had his gun.
'That call will bring guards down here at once!” Thorn cried. “Quick — the drain by which we got in here! It's our one chance now to get to the space-ship court!'
They ran down the short dungeon corridor to the place where the drain opened. The inertrum bars had been reset in new cement to repair the drain-grating, Thorn saw instantly.
He leveled his gun and triggered rapidly. The bursting flares of blinding energy burned away the new cement, again freeing the inertrum bars. As Gunner Welk bent and tore loose the bars, Thorn heard over the roar of the storm a rush of running feet.
'They're coming!” he cried, and leaped headfirst down into the narrow tube. The others followed him.
Thorn writhed down the cramped pipe with frantic haste, ahead of the Mercurian and Venusian. He heard distant yells as soldiers burst into the dungeon which they had just quit.
In a moment Thorn emerged head first into the place where the five citadel drains converged into one big tube. Water was rushing down here, flowing down through three of the pipes that drained courts open to the raging storm.
'This is the drain that leads up to the space-ship court!” he cried, scrambling into the right-hand pipe.
As he crawled at the head of his comrades up this different pipe, icy floods of water from above smashed unceasingly into his face. The drain was almost full of down rushing water. Blinded, gasping, he fought upward through the tube until he glimpsed the grating above, outlined against terrific red lightning flares.
Thorn drew his gun and fired up at the grating through the rushing water. The whizzing flare of bursting atom-shells above was almost drowned by another appalling burst of scarlet lightning, accompanied by a tremendous shock of thunder.
He pushed on upward through the streaming water. His hands found the bars of this grating, loose where their ends had been exposed by burning away of the cement. With a convulsive effort, Thorn pushed the bars upward and scrambled up into the court.
The full fury of the tremendous Saturnian storm beat upon him in this open court. Rattling showers of big hailstones crackled like musketry, torrents of icy rain smashing down upon him from the black sky. Gunner and Sual Av were scrambling up out of the drain to his side.
Blinding red. lightning arced across the heavens in awful, burning splendor, and showed Thorn two small space-cruisers parked near the center of the court. It also showed him that a troop of guards was running hastily out from the other side of the court.
'They've guessed we'd make for these ships. Come on before they cut us off!” he yelled hoarsely to his
