"Easy, Astro," said Strong, standing behind the big cadet. "Pull that line up slowly and gently."

"Yes, sir," gasped Astro. He didn't have to be told to pull the rope with caution. He knew only too well that the slightest jar or bump against the side of the shaft might dislodge Roger's unconscious body from the tangle of line, causing him to fall to the bottom of the shaft. How far down the shaft went, none of the anxious spacemen around the hole in the splintered floor knew. And they didn't want to use Roger's body to find out!

"I'll give you a hand, Astro," said Commissioner Hawks. He reached for the line, but the big cadet warned him away.

"That's all right, sir," he said. "He's almost up now."

Astro pulled gently, hand over hand, until Roger's limp body was a mere foot from the edge.

"Grab him, quick!" he panted.

Immediately Strong and Hawks were down on their knees at the edge of the hole. Each taking an arm, they pulled Roger out and laid him gently on the floor of the shack. They crouched over him and began a quick examination.

"How is he, sir?" asked Tom, hovering anxiously over the still form of his friend. "Will he be all right?"

Strong didn't answer for a moment, continuing his hurried, though careful check. Then he sat back on his heels and sighed in relief. "A few bruises but no broken bones, thank the universe. He's just suffering from shock. A day or so in sick bay and he'll be good as new."

"I'll take him over there right away, Steve," offered Hawks.

"Thanks, Mike," replied Strong. Then as he and the commissioner lifted the still form of the cadet and started to carry him out of the shack, he turned to Astro. "Blast over to the Polaris and call Solar Guard headquarters in Venusport. Tell them to send an emergency crew down here right away."

"Aye, aye, sir," snapped the big Venusian and dashed out of the shack.

Turning back to Hawks, Strong said, "Corbett and I will stay here and try to find out where that shaft leads."

"All right, Steve," nodded the commissioner. "Too bad we had to find out where that dirt came from the hard way."

Reaching the jet car, the two men placed Roger in the back seat, and Hawks slid in under the wheel to start the powerful jets. Just then Astro, racing back from the Polaris, pulled up breathlessly.

"Solar Guard crew is on the way, sir," he reported. He glanced anxiously into the back seat of the jet car.

"All right, Astro," said Strong gently, "take care of Roger." Strong gestured to the back seat and without a word Astro leaped in beside his friend. Hawks stepped on the accelerator and the car shot away in a roar of blasting jets.

Tom and Captain Strong watched the car disappear and then turned back to the shack. Each felt the same emotion, an unspoken determination to see that Wallace and Simms paid dearly for causing the accident.

Re-entering the shack, they began a careful examination of the shaft. Strong played his emergency light down the sides, but the beam penetrated only a short distance.

"We'll leave a note for the emergency crew," said Strong. "Our belt communicators might not work so far underground."

"You're going down, sir?" asked Tom.

Strong nodded. "If necessary. Tie that valve on the end of the rope Astro used and lower it into the shaft. If we can touch bottom with it, we'll climb down and see what Wallace and Simms were after."

"Yes, sir," said Tom. He took the length of rope, tied the heavy metal valve to the end, and began lowering it into the shaft. Strong continued to play the light down the shaft until the valve disappeared into the darkness.

"Rope's getting short, sir," warned Tom. "Only have about two hundred feet left."

Strong glanced at the remaining coils of line on the floor. "I'll get more from the Polaris, if we need it," he said. "How long was that line to begin with?"

"It's a regulation space line, sir," said Tom. "Astro took it out of the emergency locker. It's about twelve hundred feet."

By this time the line, hanging straight down the shaft, had become increasingly heavy. Suddenly it grew slack.

"I think I've hit bottom, sir," cried the cadet. "But I can't pull the valve back up again to make sure."

Strong grabbed the end of the line and helped the cadet pull it back up a short distance. Then they dropped the line again and felt a distinct slackening of weight.

"That's bottom all right," said Strong. "Take this end of the line, run it out of the window on your right, and back through the one on your left. Then make it fast."

"Yes, sir," said Tom. He jumped out of the window, trailing the rope after him, and reappeared almost immediately through the other window to tie a loop in the line. After checking the knot and testing the line by throwing his full weight against it, Strong stripped off his jacket and wrapped it about the line to prevent rope burns. Then, hooking the emergency light on his belt, he stepped off into the shaft. Tom watched his skipper lower himself until nothing but the light, a wavering pin point in the dark hole, could be seen. At last the light stopped moving and Tom knew Strong had reached the bottom.

"Hallooooooo!" The captain's voice echoed faintly up the dark shaft. "The belt communicators don't work!" he yelled. "Come on down!"

"Be right with you, sir!" yelled Tom. He scratched a message on the wooden floor of the shack for the emergency crew. Then he stripped off his jacket, wrapped it around the rope, secured the light to his belt, and stepped off into the darkness.

"Captain Strong!"

Slowly, his hands tight around the rope through his jacket, Tom slipped down the deep shaft. He kept his eyes averted from the black hole beneath him, looking instead at the sides of the shaft. Once, when he thought he had gone about seven hundred feet, he saw that he was passing through a stratum of thick clay and could see the preserved bones of long-dead mammals, protruding from the side of the shaft.

Finally Tom's feet touched solid ground and he released the rope. It was cold in the bottom of the shaft and he hastily put his jacket back on.

"Captain Strong?" he called. There was no answer. Tom flashed the light around and saw a low, narrow tunnel leading off to his left.

He walked slowly, and the newly dug sides of the tunnel seemed to close in on him menacingly. It was quiet. Not the blank silence of space that Tom was used to, but the deathlike stillness of a tomb. It sent chills up and down his spine. Finally he stepped around a sharp bend and stopped abruptly.

The Solar Guard officer was stooping over, his light resting on the ground, reading something he held in his hand. He looked up at Tom and jerked his thumb back over his shoulder. Tom flashed his light in that direction.

"By the rings of Saturn!" exclaimed Tom. There in front of him, ripped open like a can of sardines, was the gleaming metal skin of the time capsule! The dirt floor of the tunnel around Strong and beside the capsule was littered with audio spools, sound disks, micropapers, and stereo slides.

Tom kneeled down beside his skipper and stammered, "What—what does it mean, sir?"

"It means," answered Strong slowly, "that we're dealing with two of the cleverest men in the universe! If they've stolen what I think they have, the entire Solar Guard, Solar Alliance, and just about everyone in the universe is at their mercy!"

"How do you feel, Roger?" asked Astro.

The blond-haired cadet sat up in bed, dangled his feet over the side, and rubbed his neck. He groaned as he moved. "I don't think I'm going to dance much this month, if that answers your question. I feel like every bone in my body was broken!"

"They very nearly were, Cadet Manning," said the medical officer, standing near by.

"What happened, Manning?" asked Commissioner Hawks.

"I really don't know, sir," replied Roger. "I was moving the junk out of the corner of the shack so I could examine it. I was piling it up in the middle of the floor when—wham—something gave way and I took a header into nowhere!" He looked at Astro. "Now suppose you tell me what happened!"

Astro told Roger about finding him dangling at the end of the tangled feed lines. Then he said, "Tom and Captain Strong are out there now, waiting for one of the Solar Guard emergency crews."

"Well, what are we hanging around here for?" asked Roger, and hopped off the bed. He groaned, staggered, and then straightened up. "Nothing to worry about," he said, as Astro rushed to his side. "I'm as good as new!"

"What do you say, Doctor?" asked Hawks.

The doctor hesitated a moment and then smiled. "Well, Commissioner, Cadet Manning has several strained muscles in his back, but the best treatment for that is exercise."

Hawks nodded and signed a release slip which the doctor gave him. Astro helped Roger put on his space boots, and five minutes later they were speeding back to the exposition grounds in the commissioner's jet car. As they sped through the streets, the two cadets speculated on what they would find at the bottom of the shaft. Arriving at the shack, they were immediately challenged by an enlisted Solar Guardsman.

"Halt!" said the guard gruffly. "Advance slowly for recognition!"

With Commissioner Hawks leading the way, Roger and Astro walked up to the guard.

"Say," said Roger, nudging Astro, "look at what's going on around here!"

"Yeah," agreed Astro, wide-eyed. "Something must be plenty hot to have guards posted!"

Hawks was immediately recognized by the guard, but he still stubbornly demanded proof of their identity. Hawks, Roger, and Astro hauled out their Solar Guard identification disks, small metal plates with their images engraved in the shiny metal. On the other side was a detailed description of the bearer.

"Very well, sir," said the guard and let them pass.

In the pale light of dawn, feverish activity could be seen taking place around the shack. Two huge jet vans, filled with every possible piece of emergency equipment, were parked near by. The Polaris had been taken over as a temporary headquarters and the area was crowded with scarlet-clad enlisted men. Astro could hear the hum of generators on the Polaris and immediately felt concern for his power deck.

Proceeding to the shack they were again challenged by a guard and again had to produce their identification disks before entering. Once inside, they were amazed at the transformation. An aluminum tripod, ten feet tall, had been erected over the hole in the floor, and several steel cables, connected to a motor-driven steel drum, were looped over the apex of the tripod, one hanging straight down into the shaft. A thick plastic hose hung over the edge of the shaft, jerking spasmodically as air was pumped into the dark hole.

"By the craters of Luna," cried Hawks, "what's going on here?"

A young lieutenant stepped up to the commissioner and saluted sharply. "Lieutenant Silvers, sir. Second-in-command to Captain Allison of the emergency crew."

Hawks returned the salute and Lieutenant Silvers continued.

"Captain Strong, Cadet Corbett, and Captain Allison are at the bottom of the shaft, sir. The cage will be up in a moment and you may go down if you care to."

"Thank you, Lieutenant," said Hawks.

"Congratulations, Cadet Manning," said Silvers. "I understand you had a close call in the shaft."

"I did, sir," said Roger. "It was very close."

A light suddenly flashed on and the four spacemen turned to watch a large wire cage rise out of the shaft. It was built in three sections, each seven feet high. A ladder on one side of the cage gave easy access to the higher and lower levels. Astro climbed to the top section while Hawks took the lower. Roger stepped into the center section to avoid a climb. An enlisted man secured the gates and turned on the motor. The cage dropped through the shaft with sickening speed.

A minute later it began to brake slowly, finally coming to a dead stop at the bottom of the shaft. They were met by a Solar Guardsman who directed them into the tunnel, now illuminated by a row of flowing, self-powered emergency lights. Silently, but with rising excitement, the two cadets followed Hawks through the brightly lighted shaft, a thousand feet below the surface of the planet.

Turning the last corner in the tunnel they came upon Strong, Tom, and Captain Allison huddled near the torn side of the time capsule. They could hear Strong talking to Tom.

"There is a vault on every spaceship in the Solar Alliance, Tom," Strong was explaining. "The vault is locked before blast-off and opened after landing by a light-key operated only by a trusted spaceport security officer. This key flashes a series of light vibrations, in sequence, into the electromagnetic lock on the vault. It's really nothing more than a highly developed flashlight except that it flashes multiple combinations of lights, each containing certain electronic vibrations. The electromagnetic lock can only be opened with the proper combinations of colors and vibrations flashed by the light-key. Of course each ship has a different code of colors and vibrations, but the code itself wouldn't be hard to crack. The big thing would be to have an adjustable light-key, so that if one combination of colors and light vibrations do not work, you can try another. In that way you could open any energy lock on any vault in the system."

"And Wallace and Simms—" Tom hesitated.

"Yes, Corbett," said Strong grimly. "Wallace and Simms stole an information sound spool from the capsule. On that spool was a detailed description of the energy lock and the adjustable light-key. There were only seven keys in the system up to now. If we don't catch Wallace and Simms, there'll be eight."

"Great galaxy," Commissioner Hawks broke in. "This will ruin the exposition! The Alliance will close it after—"

Strong waved a calming hand at Hawks. "I've already spoken to Commander Walters at Space Academy, Mike," he said. "He wants this to remain a secret. No one knows about it besides us, and no one will. I'm taking your oaths, your spaceman's word, that it will remain a secret. There's no use in starting a panic. You'll keep the exposition going as if nothing had happened."

"But what can the Solar Guard do, sir?" asked Tom.

"We'll start the greatest search the system has ever seen," replied Strong calmly. "But the order for their arrest will be issued for some other violation." The Solar Guard officer suddenly noticed Roger for the first time.

"Oh, Manning!" he said, smiling. "Good to see you. How do you feel?"

"O.K., sir," replied Roger. "But I'd feel a lot better if those space crawlers didn't have the combination to every safe and vault in the universe!"

Strong nodded. "This is one of the cleverest crimes in history. And in searching for Wallace and Simms, we'll have to be twice as smart as they are!"

"Yes, sir," said Tom. "First we have to figure out what they will do, and then figure out how we're going to beat them!"

"That's right, Tom," nodded Strong. "And by the stars, if we don't beat them, the only safe place left for the credits and securities of the people in the system will be behind rows of paralo-ray guns!"