Julian Epworth reasoned that his departure from Salt Lake City was a profound secret. The fact that an airship carrying gold was on the way to Los Angeles convoyed by armed airplanes had been kept inside of the office. Because of this Epworth thought that he had an easy job.

“What’s the big idea about all this fancy maneuvering?” Billy Sand inquired curiously as Epworth gave the order to close up a little on the other nine planes flying in a straight line ahead in military formation. “You are acting as if there is a war on, and if we were trying to hatch a machine gun nest.”

“Now that we are up in the air, and there is no chance of a leak I will explain. The twin red and green lights that you see ahead are on one of our airplanes carrying a gold shipment consigned to the mint. Recently a plane similarly loaded disappeared, and our company lost a million dollars. We do not propose that such a steal shall be repeated.”

“A million! And this crate ahead is carrying that much?”

“It is carrying two million. But,” Epworth’s lips twisted determinedly, “I do not think that an air pirate will be able to get away with it—not as long as these ten little babies can shoot.”

Julian Epworth was the head of the secret service of the Atlantic-Pacific Airlines, Inc., and he imagined that his plans had been extremely well laid.

Billy glanced up at the clear sky, picked up the signals, and, in obedience to Epworth’s command, closed in on the four planes flying on the left of the large passenger ship in the lead. A ship launched secretly into the air in the dead of night, and picked up on the desert by an escort of ten planes, should certainly be safe from a robber.

“Not a chance in a million that we will be stopped,” he remarked thoughtfully. “Look at the moon and the stars! We could see a plane ten miles away, and get it long before it could get in shooting distance.”

Feeling in a good humor and perfectly safe, Epworth tuned in on the radio—just loud enough to bring the news of the world to them, and not loud enough to give a warning to any other flyer in the sky that might be secretly approaching.

Suddenly Billy leaned toward his companion excitedly, and caught his arm.

“Did you hear that? I am speaking about that noise that is coming over the radio.”

“Of course I heard it.”

The radio was saying:

“This is Clarence Ainslee, astronomical observer at Mount Wilson Observatory. Are you looking at the moon? If not, get a large telescope and look at the extreme western extremity of the Sea of Vapours. You will see something you never saw before. There is a lake or sea forming there. At least that is the judgment of astronomers.”

“What do you think about it?” Billy asked.

“Horse radish.”

Both aviators looked toward the bright shining full moon.

“But,” Epworth remarked, “we could not tell anything with our naked eyes.”

“In addition to the appearance of a new lake,” the radio continued, “vegetation is appearing not far from the eastern border of the water. The mystery of this is now puzzling the scientific world.”

“Let them puzzle,” Epworth muttered as he switched the radio dial. “I should worry.”

“This is the news report from the morning Blade,” they heard the radio say. “Station WGCF. The report has just come in that twenty masked men, all of whom spoke a foreign tongue, have robbed the Swift & Co. laboratory. They lined up the seventy chemists and their assistants, and while the gunmen held them and their helpers the bandits looted the plant. Thousands of dollars in liquid air, saltpeter, and chemicals were carried off in two enormous airplanes, dim shadowy things that stretched out two thousand feet in length.”

“Some little airplane. I’d like to see it!”

“Airplane?” Billy snorted indignantly. “They are using dirigibles of course.”

“What do you suppose they wanted with all that nitrogen and fertilizer?”

“Couldn’t guess in a million years.”

Epworth sat up straight. He had caught a view of two wriggling red lights ahead.

“There are the signals,” he cried excitedly. “Something is going on ahead.”

Both aviators went into action. Epworth seized the controls and Billy grabbed a machine gun. Both were still thinking about the long cylinder-like airplanes described by the radio. Epworth kept his eyes fixed on the airship carrying the gold. A red rocket shot out suddenly from the side of this airplane; followed by another. These signals were answered by nine planes that were following Epworth’s guidance through the silent night lanes.

To one who did not understand, the sky looked like a pyrotechnic display.

Like avenging demons the entire convoy started toward the plane sending out the distress signals, sweeping through the sky without lights, and their silencers hiding their approach. But what they saw caused every aviator and every machine gunner to pause for a second in astonishment.

An immense airship, not less than two thousand feet long, was hovering over the passenger Douglas, guiding its movements, and twenty men were running down a ladder that had been let down into the aviator’s seat of the Douglas.

Epworth, who was leading the formation of five on the larboard side, did not permit his astonishment to delay action. With a jerk he seized the control, slammed the stick into his stomach, banked slightly, leveled out until the side of the big airship was in line with his machine gun, and with a hoarse cry opened a broadside at the sky pirate—for pirate he was certain the big plane was.

When he fired he was not over one thousand feet from the pirate, and it was impossible to miss. In addition to this he had come up with a big surprise—feeling certain that the air bandits did not know that the treasure ship was convoyed. He expected to see his rain of lead tear through the cowling of the stranger and deal death and frenzy. His example was followed by every scout plane on the larboard side. A second later the five planes on the starboard swept up and poured a fierce rain of lead at the stranger. It was a barrage from both sides that it seemed would destroy anything earthly.

Yet the pirate floated serenely in the air as if it had been bombarded with peanuts, its secretly-constructed armor turning machine bullets like pellets.

Epworth give the signal, and again both formations poured their hurricane of death at the pirate. But when this bombardment seemed to pass harmlessly through the stranger, Epworth changed his tactics. He aimed at four men who were climbing down the ladder from the pirate into the Douglas. This time his shots cut the ladder into ribbons, and the four men tumbled down into the Douglas. Epworth, while feeling that he had full authority to do battle, wanted to capture the pirate and not kill the men. In this he succeeded, as to the killing, as the four pirates fell on top of the Douglas, or into the aviator’s seat.

At this moment the bandits got to fighting. Two sheets of mysterious flames burst simultaneously from both sides of the immense thing, and then all became still.

But those two broadsides were enough. The ten convoy airships conked, whirled over in the air, and began to fall.

“Jump, Billy!” Epworth cried out loudly. “Jump!”

There was need. The battle was over, and the pirate plane, with the stolen Douglas now under complete pirate control, passed away into a dim shadow. The twenty occupants of the destroyed convoy planes jumped out almost at the same second, and sprang as far away from their falling crates as possible.

Epworth’s umbrella opened within ten seconds. He saw Billy shoot by like a chunk of lead. Billy was his best chum, and his heart sank with the thought that he would be dashed to pieces against the ground. Frantically he leaned out. Other pilots were going by but he managed to keep his eye on Billy. Finally he straightened up with a cry of relief. Billy’s parachute was spreading.

“Safe,” he cried, “but great heavens what a battle! That plane’s sides are bullet proof, and it rides the sky as if it owned it.”

He looked upward. All he could see above his head were the stars. These were blotted out by the rapid approach of the earth, and the peak of the high mountain passing by him.

He landed safely but what would the president of the Air Company say when he returned with this terrible and unexpected disaster to report?