small rings on his thighs and held his arms out parallel to the ground, thus stretching taut the triangular wing-membranes between his side and his extended arms. In each hand he held a cylinder, by means of which he could operate the small gravity-nullifier on his back.
As the motor started to drone, Brink gave a little leap and soared blithely into the air. At an altitude of a hundred meters or so, he leveled off and flew swiftly toward the distant buildings, his artificial wings fanning the air with rhythmic, sweeping strokes. In a few minutes he had reached a point where he could easily read the inscription on the roof of the octagonal edifice toward which he was winging:
Earth Republic Space Navy
Interplanetary Outpost
Ganymede—Jupiter System
Bringing his arms to his sides, Brink fell like a wounded bird until he was only about twenty meters from the ground. Then he spread his wings, described a neat loop and alighted gracefully on the roof of the building. Dropping through a trap door, he walked briskly to Colonel Steiner's office.
Motioning for Brink to make himself comfortable in a chromium-framed pneumatic-cushioned chair, the Colonel began, "This time I have a very difficult assignment for you, Captain."
Brink's eyes sparkled as he declared, "I'm glad to hear that, Sir. It's nearly a month now since I did anything that could be classed as exciting."
"Don't worry," the old man grinned. "You'll probably get plenty of excitement on this trip. I'm sending you to Titan."
"To Titan?" Brink exclaimed. "Surely you don't mean the sixth satellite of Saturn, do you?"
"That's precisely what I do mean."
"But Titan hasn't been explored yet. We don't even know if it is habitable."
"We didn't until a few hours ago. But now we know that it is not only habitable but very much inhabited as well. Two citizens of the Earth Republic are there now—in trouble. The Secretary of Interplanetary Relations has ordered me to send an expedition there immediately. I have selected you as the logical man to take charge of this work."
"Thank you, Sir."
"That's all right. You will, of course, want to know the purpose of the expedition. We have been ordered to find and rescue the Valentine Sisters."
"What! Again?" Brink ejaculated.
"Yes! Again! I don't blame you for being disgusted. This is the fourth time the E. R. S. N. has been called on to save those meddlesome damsels from the consequences of their eternal quest for thrills. Previously their exploits have been confined to the unexplored portions of Mars and Venus where our garrisons were near to help them if they got into trouble. This time it looks much more serious. There really ought to be a law passed to prevent immature, irresponsible girls from getting into interplanetary messes."
"Nevertheless, you can't help admiring the Valentine twins for their pluck," Brink remarked. "There aren't many girls in their twenties who would have the guts to navigate a rocket ship into remote regions of space as they have done."
"Don't waste your admiration on them, Captain," said Steiner. "They are thrill-seekers and publicity hounds."
"Maybe so. But while they are acquiring their thrills and their notoriety they also have gone through the motions of gathering scientific data."
"I suppose they have done some good," the Colonel growled. "But that's neither here nor there. Right now your job is to locate the Valentine Twins and bring them back to earth. Take a look at this." He handed Brink a metal cylinder about a meter long and fifteen centimeters in diameter. Frank recognized it as a help-rocket such as are used to summon assistance for space ships in distress.
"It was picked up by the crew of the space-freighter, Hercules," Steiner explained. "This was found inside of it."
Brink took the scrap of paper, which the general handed to him, and read the following message: "Vera and Velma Valentine—calling for help. Our rocket-ship is wrecked on Titan about three kilometers north of a city of cones on the shore of a large orange-colored lake. We are surrounded by scores of horrible, shapeless creatures. They are closing in on us. There is just time to dispatch this rocket. Come, help us, quickly, please!"
"Shall I keep this?" Brink asked.
"You may as well. Not much to go on, I'm afraid, but it's all we have. By exercising your usual resourcefulness, I hope you will be able to accomplish the task."
"How many ships do you think I shall need?"
"You may need the whole fleet, but I'm afraid I shall be able to spare only one twenty-meter ship."
"Only one ship?" Brink exclaimed. "One small ship to fight the whole population of Titan? Why, it just isn't in the cards to"
The Colonel interrupted him with, "Sorry, Frank, but one ship is all I can spare. Several things have happened within the last few days—things that will tax our forces to the limit. Yesterday a revolution broke out on Io. The Universe Mining Corporation is having plenty of trouble at the platinum mines on Callisto. As if that wasn't plenty, the space pirates are up to their old tricks—holding up and robbing the bullion ships. I really need every ship and every man in the service. If I had my way, I'd let the Valentine sisters work out their own salvation, but orders are orders. For political reasons we must at least go through the motions of trying to rescue them, but one small ship is the most I can take away from our regular work. I guess you know what that means. On a long trip like that you'll need every cubic centimeter of storage space for fuel, oxygen, water and food. There will be room for only two other men besides yourself."
"You have certainly given me a good job," Brink grinned. "All I have to do is to conquer a whole nation of unknown enemies with one ship and three men."
"I realize that your task will not be an easy one," the general conceded. "But I'm hoping you will make up for your lack of numbers by your well known ability as a strategist. After all, if it is a question of open warfare, perhaps even the entire E. R. S. N. fleet would not be powerful enough to accomplish the objective. And when it comes to stealth and strategy, the smaller the force is, the more likely it is to succeed."
"Very well, Sir," Brink saluted. "I'll do my best, Sir."
"You don't need to tell me that," the old man said as he gave Frank an affectionate pat on the shoulder. "In recognition of the difficulties you are likely to encounter,
