Gradually fierce resolve began repossessing him. The men of the TSS did not give up until they were dead! And this mission of his was the most important any man of the Terrestrial Secret Service had ever been assigned. He must not give up! He would not, while he was alive!
He stared around the cell with narrowed, desperate eyes. If he could just get out of this rat-trap, just get to the cabin of Jurk Usk…
He could get out! The inspiration came to Rab Crane's taut brain in a flash. It would be a desperate way of escape, and perilous. Yet it was the only way, and he would try it!
He was startled out of his quivering intentness by a light knock, a voice outside the locked door. Through the barred opening, Lalla Dee's soft face looked in at him.
The Venusian girl's dark eyes were troubled and anxious.
"They let me come down to see you for a few moments!" she said. "Oh, I know you're not guilty of these murders!"
Crane's nerves relaxed a little. He even managed a grin.
"Good kid," he told her through the bars. "I'm not guilty and I can prove it when we reach Earth. But there're more important things at stake than my own fate, just now."
He pressed closer to the bars, lowering voice.
"Lalla Dee, I want you to do something for me. Will you?"
Her head bobbed, her clear eyes looking anxiously into his.
"I'll do anything I can," she promised.
"I want you to find out for me just what cabins are occupied by those who sat at our dining table last night," he said.
"Why, I don't see — but I can do that, all right. Wait, I'll go now," she said.
She departed and Crane waited tensely. He had not asked her simply for the location of the Jovian's cabin, because he did not even want her to suspect his paramount interest in Jurk Usk. The girl must not become involved in his desperate scheme.
She was soon back, obviously still perplexed by his request but with the information he wanted.
"The cabins are all on the second cabin-deck, like yours and mine," the girl told him. "That of Jurk Usk is two doors off the main corridor, toward the stern. Kark Al, the Martian, is three doors beyond that. And the cabin of the young Earthman who was poisoned is directly opposite the Martian's. You know where the rest are."
"I know," Crane said swiftly. "You've helped me a lot, Lalla Dee. I want you to go back up now and forget all about this, and no matter what happens to me, don't you say anything that will get you mixed up in this affair."
"Norman, you sound as though something awful might happen to you," she told him distressedly. "What is it?"
"I'll be all right," he repeated "And you're a swell girl, Lalla Dee."
She left and Crane paced the floor, seething with excitement. If he could just get to Jurk Usk's cabin…
He waited impatiently for the coming of the ship's night. When finally the lights had been turned off and the passengers had retired, and the whole craft silent except for the occasional passing step of a sailor and the throbbing of the ventilators, Rab Crane began to act. First he removed his shoes and sox.
Then he twisted with all his strength at one of the metal posts that supported his bunk, until he tore it loose. With this short, thick club in his hand, he climbed upon the now shaky bunk and reached up toward the grating of the ventilator-tube.
The tube was almost two feet across, a round pipe connected with the main ventilation system which dispersed oxygenized fresh air constantly to every room in the ship. Crane inserted his club in the grating and pried. The grating came loose with a little snap, and he poised, listening. But, apparently, no one had heard.
He stuffed the club into his trouser band and drew himself up into the ventilating tube. He got one shoulder in, then the other. The tube was a terribly tight fit but he inched steadily forward in it. In his face beat the constant flood of fresh, tangy air, and in his ears throbbed the distant pumps. Soon the tube opened into a vertical pipe, a somewhat larger one leading up to the decks above. Crane climbed slowly up this, bracing himself with bare hands and feet against the smooth sides.
Blindly he wormed upward in the dark pipe until he came to the place where a branch tube led horizontally into the second cabin-deck, his goal.
Now he began to count the branch tubes that led off into the separate cabins. Two branches further should be the tube leading to Jurk Usk's cabin. And Jurk Usk, no matter how diabolical his ingenuity, would never expect death to come to him through the ventilator!
Stealthily Crane inched forward and into the second branch tube. At its end was a light grating. Crane peered down through this into the dark cabin of the Jovian, located the dark bulk of the bunk.
Crane gently opened the grating and dropped soundlessly into the cabin. As he landed, Jurk Usk awoke!
Like a wildcat, the TSS man sprang. As the Jovian sat up, the club fell on his head and he sank back, stunned.
Swiftly Crane tore strips from the blankets and bound and gagged the man of Jupiter. Then he turned on the lights and looked around the cabin, his heart beating rapidly.
"He must have the brain somewhere in the cabin," Crane told himself as he started a swift search.
Ten minutes later he stopped, thunderstruck by the results of his search.
"Good God, the brain isn't here! Then Jurk Usk isn't the killer, after all!"
He had searched every cranny. The brain of Doctor Alph was not here, and his inspection of the Jovian's belongings had convinced Rab that Jurk Usk was really what he claimed to be a shipping magnate and not a secret agent.
Then neither Kin Nilga nor the Jovian, after all, was his deadly opponent! Yet they were the only men on board with the enormous strength the killer possessed. If neither of them was the murderer, who could be? The logical answer to that question forced itself on Rab Crane's brain. He could not believe it, could not understand it, yet it rose before him with the cold force of reason. Glistening perspiration broke out on the Earthman's bronzed brow.
Leaving Jurk Usk bound, Crane climbed back into the ventilating tube and inched downward again through the great pipe.
Slowly, silently he crawled forwards turned off at the third next branch tube. Again Crane wormed toward the grating opening into a cabin. And this cabin was lighted.
Even before he reached the grating, Crane heard a voice that made his hair stand on end. A thin, monotonous metallic voice, utterly without expression.
And it was pleading tonelessly, "Why do you not kill me now that you have my secret? Please kill me — please kill me-"
Rab Crane had found the stolen brain at last! For this voice he heard was the mechanical loud-speaker voice through which the living brain of Doctor Alph was speaking!
CHAPTER IV
YELLOW DOOM
Every nerve quivering, Crane inched forward. At last he stopped, his face almost against the grating, peering down into the lighted cabin. His gaze riveted on a table that stood between the bunk and a wooden crate.
On that table stood the thing he had risked his life to trail — a black metal case eighteen inches square. It had recording-dials in its face, a tiny microphone earphone, and the round diaphragm of a small loudspeaker. And inside that innocent-looking case, in its preserving serum, still lived the brain of Doctor Alph!
And Doctor Alph's brain was still speaking in that dreadful, toneless voice.
"Kill me! Please kill me-"
"Not yet, my dear Doctor," mocked the man standing in front of the braincase. "The death you crave will not come until I have completely tested this secret of yours."
That mocking man who spoke, the diabolical brain-thief and murderer, was Kark Al, the little Martian!