While Andy lay senseless on the floor of the hangar with the flames from the oil-soaked waste mounting higher, a shadow appeared in the doorway. It was Blatz, whom Andy had surprised in the hangar as he was about to attempt the destruction of the Goliath.

The German observer crept closer to the flames and it was not until he was almost at the blaze that he discerned the inert form of the assistant pilot.

“Andy,” he cried, “Andy!”

There was no answer and Blatz acted with sudden determination. He picked up the coat which Andy still clutched and used the garment to beat out the flames. That task accomplished he turned on his flashlight and bent down to examine the lump on Andy’s forehead. The young airman groaned and Blatz chuckled grimly. The game was nearly over. He was glad.

He managed to pick Andy up and carried the now half-conscious American out of the hangar and into his office, where he turned on the light.

Andy came to several minutes later and finally focused his eyes long enough on one spot to see Blatz standing in front of him.

“I’m on to you,” cried Andy, struggling to get out of his chair. “You’re trying to destroy the Goliath.”

“Easy, Andy, easy,” urged Blatz. “You’ve had another nasty bump on your head. The Goliath is all right.”

“The last I remember is falling,” said Andy. “How did I get in here and what are you doing around the hangar at this time of night?”

“You took a tumble, all right,” agreed Blatz, “and the match you had in your hand fell into a handful of greasy waste. You’d chased me out of the hangar but if I hadn’t been curious when you failed to follow, the whole thing might have burned up. As it was, I got back in time to put out the fire before it got to you or the Goliath.”

Andy looked at the speaker with incredulous eyes.

“If that’s true,” he said, “I have done you a great wrong.”

Before the observer could reply, Bert burst through the door.

“Big news,” he said. “The Rubanian air force rebelled this afternoon and forced Dictator Reikoff clear out of the country. I just got that bulletin over in the radio shack.”

“You’re sure there’s no mistake?” asked Blatz.

“Positive,” replied Bert. “It was an Associated Press dispatch broadcast through the courtesy of one of the Louisville papers.”

Blatz looked at Andy and they smiled understanding.

“What’s the joke,” demanded Bert.

“There isn’t any joke,” replied Blatz gravely, “and I can now tell you the truth. I am Lieut. Serge Larko of the Rubanian air force. I was assigned to special duty as an agent of the Gerka, our secret police, and my mission was to make a non-stop flight to the United States, make my way to Bellevue and bring about the destruction of the Goliath.”

Bert stared at him in speechless wonder but Andy nodded and said.

“Then you were piloting the gray monoplane we chased that afternoon?”

“Right,” said Serge. “You gave me a real scare.”

“And you went into that warehouse on the east side while we were in New York?” continued Andy.

“Right again.”

“And tonight you went into the hangar for the purpose of destroying the Goliath?”

“I started in with that purpose,” admitted Serge, “but I’m too much of an airman. After I got inside I couldn’t bring myself to damage that beautiful craft. I was about to leave when you entered and we met in the dark. You know the rest of the story.”

“I know that it was mighty fortunate for me that you came back,” replied Andy and be grasped Serge warmly by the hand. “Now that the menace of Reikoff has been removed from your homeland, I’m sure we’ll become real friends. We’ll see Dad and Captain Harkins about having you added to the permanent staff of the National Airways.”

“I’d like that,” smiled Serge happily, “but they’ll probably order me away from Bellevue or the secret service may take a hand in my case.”

“I think Merritt Timms can be made to see things my way,” replied Andy.

“When did you first suspect me?” asked Serge. “Almost as soon as you arrived,” admitted Andy. “If you remember I questioned you about Friedrichshafen and suggested that you might know Karl Staab? When you admitted that you knew Staab I decided something was wrong for as far as I know Staab never existed outside of my own mind.”

“But I really have been at Friedrichshafen,” replied Serge.

“I believed that,” said Andy, “for your technical knowledge showed you had been trained with the Germans. Now let’s go over to the hotel and see Dad and Captain Harkins.”

The conference at the hotel was interesting and successful and before the long evening drew to a close it was agreed that Serge Larko, who had assumed his real identity, should become a permanent member of the Goliath’s crew.

Even though the next day promised to be unusually busy, it was midnight before they were in bed but they were up at the crack of dawn.

Serge was happier than he had been in months and Andy felt that a great weight had been lifted from his mind. There was no further danger to the Goliath from inside sources and they were practically ready for the test flights.

Lieut. Jim Crummit, in command of the army pursuit ships at Bellevue, stopped them as they left the hotel.

“Will you want us to stand by this afternoon in case you decide to take the Goliath aloft?” he asked Captain Harkins.

“I hardly think that will be necessary, Lieutenant!” replied the commander of the Goliath. “Any flight we might make would be confined to the limits of the field.”

“Right, sir,” said the army officer as he turned and walked toward the hangars which housed the army ships.

At eight o’clock Andy, Serge and Bert gathered in the radio shack and Bert turned his set to talk with the Neptune. There was a steady crackle of interference but Bert stepped up the power with the hope that he would get through to the Neptune.

“Looks like we’re out of luck this morning,” he finally announced, “but I’ll give it one more try.” He turned to the dial again, tuning so carefully the black disks hardly moved.

“Harry’s coming in now,” he said. “I’ll have it strong in a minute.”

Bert switched over to the radiophone loudspeaker and the boys heard Harry calling, “Hello Bellevue. Good morning.”

“Good morning yourself,” replied Bert. “Have fish for breakfast?”

“Not this morning,” replied Harry. “Besides, it’s mid-forenoon out where we are. How’s the Goliath?”

Andy picked up the microphone and told Harry briefly what had taken place the night before, adding that Serge had been added to the crew of the Goliath and would make the trip to the North pole.

“I’m glad to hear that,” replied Harry over the magic waves which bridged the hundreds of miles between them. “I’ll say hello to Serge if he’ll take the mike now.”

The young Rubanian conversed with Harry for several minutes and then the operator of the Neptune signed off.

“I’ll be back on the air tonight at eight,” he told Bert. “Be sure and let me know how the Goliath behaves on her first trip out of the hangar.”

The interior of the great hangar was alive with activity that morning. Final weight checks were being made for the war department. Specifications on the total weight were very strict and builders of dirigibles were always prone to exceed the specification limit.

Captain Harkins and Andy’s father were at first one end of the Goliath and then at the other supervising the countless last minute tasks.

A tri-motor droned over the field at 11 o’clock, circled and dropped down to waddle across the fresh green of the meadow. It stopped at one side of the Goliath’s hangar and a dozen army officers, all with the wings of the air corps on their collars, descended and walked toward the hangar.

Captain Harkins and Andy’s father hastened to make them welcome and assure them that the Goliath would be ready for a walk-out test immediately after lunch.

While the builders and chief engineers of the Goliath entertained the visiting army delegation at the hotel at noon, Andy and Serge made the final inspection of the big ship. The ground crew had been drilled in its task and the operator of the portable mooring mast to which the nose of the Goliath had been fastened had thoroughly rehearsed his part.

At one o’clock the army officers, accompanied by Captain Harkins and Charles High, returned from the hotel. For the next hour the army men went over the Goliath, inspecting every yard of fabric and testing every duralumin beam. Motors were put on test, Bert demonstrated the power of his radio equipment and even the passenger cabins came in for a rigid inspection.

At two o’clock Captain Harkins stepped into the control room at the forwar............