The hatch clanked shut behind them. Inside the huge air lock of the Lady Venus, Tom, Roger, Astro and Captain Strong waited for the oxygen to equal the pressure in their space suits before removing their fish-bowl space helmets.

"O.K., sir," said Tom, "pressure's equal."

Strong stepped to the hatch leading to the inside of the ship and pushed hard. It slid to one side.

"How many jet boats do you have?" was the first thing Strong heard as he stepped through the door to the interior of the passenger ship.

"Al James!" cried Manning. "So this is your tub?"

The startled young skipper, whom Tom, Roger and Astro had met in Atom City, turned to face the blond-headed cadet.

"Manning!" he gasped.

"What's your trouble, skipper?" asked Strong of the young spaceship captain.

Before James could answer there was a sudden clamor from beyond the next hatch leading to the main passenger cabin. Suddenly the hatch was jerked open and a group of frightened men and women poured through. The first to reach Strong, a short fat man with a moonface and wearing glasses, began to jabber hysterically, while clinging to Strong's arm.

"Sir, this ship is going to blow up any moment. You've got to save us!" He turned to face Al James. "And he refused to allow us to escape in the jet boats!" He pointed an accusing finger at the young skipper as the other passengers loudly backed him up.

"Just a moment," snapped Strong. "There's a Solar Guard rocket cruiser only five hundred yards away, so take it easy and don't get hysterical. No one is going to get hurt if you keep calm and obey orders!" He turned to James. "What's the trouble, skipper?"

"It's the reaction chamber. The lead baffle around the chamber worked loose and flooded everything with radiation. Now the mass in number-three rocket is building and wildcatting itself. If it gets any higher, it'll explode."

"Why didn't your power-deck man dump the mass?" asked Strong.

"We didn't know it was wildcatting until after he had tried to repair it. And he didn't tighten the bolts enough to keep it from leaking radiation." The young skipper paused. "He lived long enough to warn us, though."

"What's the Geiger count on the radiation?" asked Strong.

"Up to twelve thirty-two—about ten minutes ago," answered James. "I pulled everybody out of the power deck and cut all energy circuits, including the energizing pumps. We didn't have any power so I had to use the combined juice of the three jet boats to send out the emergency signal that you picked up." He turned to face the little man with the glasses. "I had a choice of either saving about fifteen passengers on the jet boats, and leaving the others, or take a chance on saving everybody by using the power to send out a message."

"Ummmmh," said Strong to himself. He felt confidence in a young spaceman who would take a decision like that on himself. "What was that Geiger count again?" he asked.

"Must be better than fourteen hundred by now," answered James.

Strong made a quick decision.

"All right," he said, tight-lipped, "abandon ship! How many passengers?"

"Seventeen women and twenty-three men including the crew," replied James.

"Does that include yourself?" asked Strong.

"No," came the reply.

Strong felt better. Any man who would not count himself on a list to survive could be counted on in any emergency.

"We'll take four women at a time in each jet boat first," said Strong. "James, you and I will operate the jet boats and ferry the passengers to the Polaris. Tom, you and Roger and Astro get everybody aboard the ship ready to leave."

"Yes, sir," said Tom.

"We haven't much time. The reaction mass is building fast. Come on, James, we have to rip out the seats in the jet boats to get five people in them." Strong turned back into the jet-boat launching well.

"May I have the passenger lists, Captain?" asked Tom, turning to James. The young skipper handed him a clip board with the names of the passengers and crew and followed Strong.

"We will abandon ship in alphabetical order," announced Tom. "Miss Nancy Anderson?"

A young girl about sixteen stepped forward.

"Just stand there by the hatch, Miss," said Tom. He glanced at the next name. "Miss Elizabeth Anderson?" Another girl, looking very much like the first, stepped forward and stood beside her sister.

"Mrs. John Bailey?" called Tom.

A gray-haired woman of about sixty stepped forward.

"Pardon me, sir, but I would rather remain with my husband, and go later with him."

"No—no, Mary," pleaded an elderly man, holding his arm around her shoulder. "Go now. I'll be all right. Won't I, sir?" He looked at Tom anxiously.

"I can't be sure, sir," said Tom. He found it difficult to control his voice as he looked down at the old couple, who couldn't weigh more than two hundred pounds between them.

"I'm going to stay," said the woman firmly.

"As you wish, Madam," said Tom. He looked at the list again. "Mrs. Helen Carson?"

A woman about thirty-five, carrying a young boy about four years old, stepped out and took her place beside the two sisters.

In a moment, the first eight passengers were assembled into two groups, helped into space suits, with a special portable suit for the little boy, and loaded in the jet boats. The red light over the hatch glowed, then went out. The first load of passengers had left the Lady Venus.

"They're pretty jumpy," Roger whispered, nodding toward the remaining passengers.

"Yeah," answered Tom. "Say, where's Astro?"

"I don't know. Probably went to take a look at the jet boats to see if one could be repaired so we'd have a third ferry running."

"Good idea," said Tom. "See if you can't cheer these people up, Roger. Tell them stories or sing songs—or better yet, get them to sing. Try to make them forget they're sitting on an atom bomb!"

"I can't forget it myself," said Roger. "How can I make them forget it?"

"Try anything. I'll go see if I can't give Astro a hand!"

Roger turned to face the assembled passengers and smiled. All around him in the main passenger lounge, the frightened men and women sat huddled together in small groups, staring at him, terror in their eyes.

"Ladieeees and Gentlemen," began Roger. "You are now going to be entertained by the loudest, corniest and most miserable voice in the universe. I'm going to sing!"

He waited for a laugh, but there was only a slight stir as the passengers shifted nervously in their seats.

Shrugging his shoulders, Roger took a deep breath and began to sing. He only knew one song and he sang it with gusto.

On the lower deck of the passenger ship, Tom smiled as he faintly heard his unit-mate's voice. He made his way to the jet-boat deck of the Lady Venus and opened the hatch.

"Hey, Astro," he called. There wasn't any answer.

He stepped inside and looked around the empty deck. Walking over to one of the jet boats, he saw evidence of Al James's attempts to send out emergency signal messages. He called again. "Hey, Astro—where are you?" Still no answer. He noticed that one of the jet boats was missing. There were three still on the deck, but an empty catapult for the fourth made Tom think that Astro might have repaired the fourth and taken it out in space for a test. The light over the escape hatch indicated that someone had gone out. It was odd, thought Tom, for Astro to go out alone. But then he shrugged, remembering how Astro could lose himself in his work and forget everything but the job at hand. He climbed back to the passenger deck.

When Tom opened the hatch to the main lounge, the sight that filled his eyes was so funny that, even in the face of danger, he had to laugh. Roger, with his hands clasped behind his back, was down on his knees trying to push a food pellet across the deck with his nose. The whole passenger lounge echoed with hysterical laughter.

Suddenly the laughter was stopped by the sound of the bell over the air-lock hatch. Strong and James had returned to ferry more passengers to the Polaris. Immediately the fun was forgotten and the passengers crowded around for the roll call.

"Where's Astro?" asked Strong, as he reappeared in the lounge.

"He's down on the jet-boat deck, sir, trying to fix another one," replied Tom. "I think he's out testing one now."

"Good," said Strong. "How're they taking it?" He indicated the passengers.

"Roger's been keeping them amused with games and songs, sir," said Tom proudly.

"They'll need it. I don't mind telling you, Corbett," said Strong, "it's a wonder to me this tub hasn't blown up already."

In less than a half hour, the forty passengers and crewmen of the Lady Venus were transferred in alphabetical order to the waiting Polaris. Roger kept up a continual line of patter and jokes and stories, making a fool of himself, but keeping the remaining passengers amused and their minds off the dangers of the rapidly building reaction mass.

"Just one passenger left," said Strong, "with myself and you three. I think we can squeeze five in that jet boat and get off here."

"That's for me," said Roger. "I'm the only man in the whole universe that's ever played to a packed house sitting on top of an atomic bomb!"

"All right, Barrymore," said Strong, "get aboard!"

"Say," asked Tom, "where's Astro?"

"I don't know," replied Roger. "I thought you went to find him half an hour ago!"

"I did," said Tom, "but when I went to the jet-boat deck, one was missing. So I figured he had fixed one and taken it out for a test."

"Then he's probably outside in space now!" said Strong. Suddenly the Solar Guard captain caught himself. "Wait a minute! How many jet boats were on the deck, Corbett?"

"Three, sir."

"Then Astro is still aboard the ship," said Strong. "He couldn't have taken a boat. James told me he couldn't repeat the message he sent out because he only had the power of three jet boats. One was damaged and left behind at Atom City!"

"By the rings of Saturn," said Roger, "a coupla million miles from home, sitting on an atomic bomb and that big Venusian hick decides to play hide-and-seek!"

"Never mind the cracks," said Strong. "We've got to find him!"

"Captain," said the little man with the round face and glasses who had first spoken to Strong when he came aboard, "just because my name happens to be Zewbriski, and I have to be the very last to get on a jet boat, I don't see why I have to wait any longer. I demand to be taken off this ship immediately! I refuse to risk my life waiting around for some foolish cadet!"

"That foolish cadet, Mr. Zewbriski," said Strong coldly, "is a human being like you and we don't budge until we find him!"

At that moment the bell began to ring, indicating that the outer hatch to the air lock was opening.

"By the craters of Luna," said Tom, "that must be Astro now!"

"But if it is," said Roger, "how did he get out there?"

From behind them, the hatch to the inner air lock opened and Al James stepped through.

"Captain Strong," he said excitedly, "you've got to come quickly. Some of the crewmen have broken into your arms locker and taken paralo-ray guns. They threaten to leave you here if you don't return to the ship within five minutes. They're afraid the Venus might blow up and damage the Polaris at this close range." The young skipper, his red-brown uniform torn and dirty, looked at the Solar Guard captain with wild-eyed desperation.

"They can't leave us here," whimpered Zewbriski. "We'll all be blown to bits!"

"Shut up!" barked Strong. He turned to Tom and Roger. "I can do one of two things," he said. "I can order you to return to the Polaris now, with James and myself, or you can volunteer to stay behind and search for Astro."

Without looking at Roger, Tom answered, "We'll stay, sir. And we won't have to search for him. I think I know where he is."

"Now that I think about it," replied Strong, "I guess there is only one place he could be."

"Yes, sir," said Tom, "down on the power deck trying to save this wagon! Come on, Roger! Let's get him!"