The usually active, buzzing Bolling Field was shrouded in darkness and looked almost completely deserted as Colonel Welsh wheeled the car up toward the main gates. When he came within twenty yards of those gates, however, there was instant proof that not everybody was asleep. Two small-sized searchlight beams cut the darkness and focused square on the moving car. Dawson, from past experience, knew that up in the little towers that housed the searchlights were a couple of machine guns that were also trained dead on the car. In addition, the captain on duty and two armed guards suddenly appeared and closed in on the car in nothing flat. And as if the twin searchlight beams were not enough, the captain snapped on a flashlight and played it straight into Colonel Welsh's face, then into Dawson's, and then into Freddy Farmer's. Just to make sure, the captain turned the light on the colonel's face once more, and then snapped it out.

"Your pass, please, sir," he said quietly.

The colonel produced it, and the captain was completely satisfied. He stepped back, saluted, and gave an order. As the heavy gates swung open, Colonel Welsh slipped the car into gear and rolled on through. Looking back, Dawson noted that the guns of the guards, and the searchlight beams, too, followed the car well inside the field. The idea seemed silly to him for a moment. Then he realized that it would be quite easy for somebody who wasn't wanted to hook a ride on the rear bumper, and thus get inside where he didn't belong.

"Yes, sir!" he murmured as he turned front again. "This is one place that would stop even Superman cold."

"I hope that's true, and I believe it is," Colonel Welsh stated.

Dawson turned his head and glanced sharply at the Intelligence Chief. An undernote in the officer's voice had a queer ring. Before he could ask questions, however, Colonel Welsh turned the car in through the wide-open doors of one of the hangars, braked it to a stop just inside, and switched off the engine. A single rafter-light threw a pale glow about the interior, and in one sweeping glance Dave saw that the hangar was empty of planes except for a single Army-Air-Forces, Wright Cyclone-powered, Vultee V-12C, attack bomber. A couple of mechanics and a technical sergeant were standing by the wing. They came over to the car at once, and gave the colonel a snappy salute.

"All set and ready, as you ordered, sir," the technical sergeant said.

Colonel Welsh climbed out of the car, and nodded.

"Very good, Sergeant," he said. "Roll her out and start her up, will you? We're going to use Captain Billings' office for a few minutes. If anybody happens to wander in, no matter who, you have my authority to send him right along on his way."

"Right, sir," the technical sergeant answered, and grinned as though he could name two or three high rankers he would just love to toss out on their ears, now that he had the permission to do so.

However, he didn't mention that little item. Instead, he snapped orders to the two mechanics, and all three of them began rolling the attack bomber out onto the hangar apron. Meanwhile Colonel Welsh led Dawson and Farmer into Captain Billings' office in a rear corner of the hangar. He snapped on the light, closed the door, waved them to a couple of chairs, and sat down at a desk. He drew six envelopes from an inside pocket of his tunic. Each envelope was heavily sealed with wax, and each was made of a peculiar-looking paper. At first glance it struck Dawson that it was oil paper, or shark's skin. At any rate, he had a sudden thought that each envelope was absolutely waterproof.

The colonel placed them in a pile on the desk in front of him, and then rested a hand on top of the pile, almost as though he expected a non-existent wind or an invisible force to snatch them away.

"You two are headed for Natal, Brazil," he began, speaking quietly. "With stops on the way at Miami, Puerto Rico, San Fernando in British Trinidad, Paramaribo in Dutch Guiana, Belem in Brazil, and Natal. You will land on the government airport at each of those points. Officially, you are making a survey flight for the Army Air Transport Command. At Miami and Puerto Rico you will contact the American commanding officer, and deliver to him in the presence of no one else the envelope that bears his name. On the authority of a letter which I shall give you to take along, you are to instruct him to guard his envelope with his life, and not to open it until the sixteenth of this month. At San Fernando, Paramaribo, Belem, and Natal, of course you will contact the officer in command of the American staff, and not the commanding officer of the airport."

The colonel paused for a moment as though permitting time for his instructions to sink in. Then he tapped the pile of heavily sealed, waterproof envelopes with his fingers.

"These contain information on perhaps the most important secret of this war!" he continued, speaking in a grave tone. "The Axis would gladly give up half a dozen divisions of troops for the possession of any one of these envelopes. And that doesn't even begin to describe how important they are. I am the only man in the world who knows of the flight you two are to begin in a few minutes. At least, I pray to God that I'm the only one. However, in view of the fact that absolutely nothing is sure in this war, I must give you this order: Under no circumstances, not even under the threat of the most horrible kind of death, is either of you to permit a single one of these letters to get into the hands of anybody but the American officer whose name is typed on the front of each envelope. Do I make myself clear?"

"Yes, sir," Dawson said with a nod.

"Definitely, sir," Freddy Farmer echoed.

"And I'm sure you do," the colonel said. "I can't help, though, but stress that point. Don't let any of these envelopes out of your sight until each has been delivered to the proper person. Make doubly sure that each of those proper persons understands what he is to do. Naturally, you'll be asked questions by those officers as to what the envelopes contain. That is one reason why I'm not even telling you, so that you can truthfully reply that you do not know. Just remember, this is the most secret mission you have ever undertaken. Guard these envelopes with your lives and see that they are delivered to the proper parties. If the commanding officer does not happen to be there when you arrive, do not give the envelope to the next in command. Stay there until the commanding officer does arrive. If you have a forced landing, play up the fact you are on a survey flight. If your plane is damaged, a wire sent to me in Washington will get an immediate reply ordering the commandant of the airfield nearest the scene of your crash to turn over a plane to you. If one of you happens to be injured in the crash, the other will carry on alone as soon as possible, without creating suspicion that the flight is not for survey purposes."

The colonel suddenly stopped talking and drew from his pocket two small vials containing a brownish liquid. He placed them beside the pile of envelopes, and looked at the two air aces again.

"If both of you are hurt badly," he said, "or if—and I pray God it will not happen—you should fall into the hands of enemy agents, or force-land on the water and be approached by a lurking U-boat, you are to take the caps from these vials and pour the contents over the envelopes. The powerful acid they contain will completely destroy the envelopes and their contents in a matter of seconds. In short, it is your sacred trust to destroy these envelopes before you die—or are captured. Now, to make sure, repeat to me the instructions I've just given you."

Dawson spoke for the pair and repeated almost word for word everything the colonel had told them.

"Well, that's all I've got to say," the Intelligence Chief said with a nod. "Here, Dawson. Three of these and a vial are for you. And the other three and a vial are for you, Farmer. Naturally, my prayers go with you for a safe and very uneventful flight. If it helps any, I personally chose you two for this flight, because—well, you've come through for me several times in the past, and I know you will again. One thing, though. If any of the envelopes fall into Axis hands, I might just as well put a bullet through my brain, because I wouldn't want to go on living. Have either of you any questions?"

"Yes, sir, I have one," Freddy Farmer spoke up.

"Then let's have it," Colonel Welsh said with a nod.

The English-born air ace hesitated a moment, and a slight flush crept up into his sun-and-wind-bronzed face.

"These chaps to whom we deliver the envelopes, sir," he said with a frown. "What if they—Well, what I'm trying to say, sir, is supposing they don't follow the orders we give them? What if they should lose their envelopes or—well, you know."

"They won't, Farmer," Colonel Welsh said with a grim shake of his head. "Each of the six officers that you will contact is not only an officer in our Armed Forces, but a carefully selected member of Intelligence as well. In short, each is one of my own men. And after you show them this letter of authority, you need not worry that they won't follow orders right to the letter."

As he spoke, the colonel drew a seventh, but unsealed, envelope from his pocket and handed it to Freddy Farmer. Then he turned his head and looked at Dawson's frown.

"Yes, Dawson?" he asked. "You've a question, too?"

"A couple, Colonel," Dave replied. Then with a shrug, "The first may strike you as stupid."

"How can I say, until you ask it?" the Intelligence officer demanded as the Yank air ace didn't go on.

"These officers we're to contact—" Dawson said presently—"is there any way we can make sure that each is the one we believe him to be? In other words, we've just got six names, Colonel. I haven't read them yet, but it's possible that neither Freddy nor I know the men from Adam as far as looks are concerned."

"A mighty good question, Dawson," Colonel Welsh said with an emphatic nod. "Just shows you've got your eye on the ball right at the start. Contact the officer, show him my letter of authority, and demand his identification. It will be a copper disc with some numbers stamped on it. Every set of numbers will add up to forty-one—the year, incidentally, of Pearl Harbor. If the numbers don't add up to forty-one, then he is not your man."

"And if they don't add up to forty-one, sir?" Freddy Farmer asked, and leaned forward.

Colonel Welsh's lips stiffened, and an agate-hard glint came into his eyes. He pointed to the letter of authority Freddy held in his hands.

"Use that to have the man placed under close arrest at once!" he said harshly. "And get in radiophone communication with me as soon as possible. If the man tries to evade arrest, tries to escape—shoot him dead on the spot! Yes, that's an unusual order, but this is an unusual mission. Now, the other question, Dawson? What is it?""When we reach Natal, sir," Dave said, "what do we do? Fly back and report to you?"

"No," the senior officer said with a shake of his head. "I'm allowing three days for you to make this stop-over flight to Brazil. That should get you in Natal by the fourteenth, the fifteenth at the latest. Put up at the Pan-Am Hotel. I will join you there on the fifteenth. I'll have another little mission for you when I get there. Well, any other questions?"

Dawson and Farmer looked at each other. Then they looked at Colonel Welsh, and each shook his head. The senior officer stood up, and as though the gods had waited for that exact instant, the Vultee's Wright-Cyclone outside broke forth with its song of mighty power.

"Then that's that," Colonel Welsh said. "There's some flying gear over there on the wall. Select what you want, and then let's get outside to the plane. I'll stake my life that not a soul has heard what we've been talking about, but four walls always get on my nerves. I like it better out in the open where I can see in all directions, and for some distance, too. But don't pay any attention to me. I'm under a slight strain, and it's trying its darnedest to get me. Stupid, of course. So select your stuff, and let's get out to the plane. God bless you, and all kinds of happy landings until we meet again in Natal, Brazil."

If they happened to be listening to the colonel's parting words, the gods of war, and death, and doom, must have had quite a laugh for themselves!