As Lieutenant Wilson quickly crossed over to the desk Colonel Fraser turned his head and looked at him in mild surprise.

"What is it, Wilson?" he asked. Then catching his breath, "Good grief, you've done it so soon, man?"

"Yes sir," Wilson replied. "A very simple numbers code. Matter of fact, sir, I fancy it's one he made up for his own use. I've decoded and typed out everything, sir. Mostly personal notes for his own use. It seems like the chap didn't care to trust to memory, so put it all down in code. But most, most interesting, sir!"

"Thank you, Wilson, and jolly quick work," Colonel Fraser said, as he took the little black book, and the two sheets of typewritten lines. Then, with an apologetic smile at Major Crandall, and Dawson, and Farmer, he murmured, "Excuse me, Gentlemen, while I glance through this stuff, will you?"

All three replied that that was all right, but even though they had shouted, "No!" in a loud chorus it wouldn't have made any difference, for the colonel was already giving his concentrated attention to the reading matter. Dawson tried to be polite and not stare at the man, but when Colonel Fraser suddenly gasped sharply, muttered something under his breath, and a look of angry bewilderment flooded his face, neither Dawson or the other two could possibly keep their eyes off him. It was almost comical, the picture. Major Fraser, Dawson and Freddy Farmer were like three eager dogs who were having the dickens of a time controlling themselves until they received the signal.

Eventually Colonel Fraser slapped the papers down on the desk with an oath, and didn't even bother to apologize. His face was flaming red, and his eyes glittered like ice cubes in the sun.

"Incredible, unbelievable!" he finally exploded. "Good heavens! There's almost as much information about things here in England as we know ourselves. That Herr Baron is a devil, I swear. He's—he's almost superhuman, the rascal!"

"Information about what, sir?" Major Crandall asked, after he had waited a polite moment.

Colonel Fraser slapped a hand on the little black book.

"About American and R.A.F. forces in England!" he cried. "The location of every drome, the types of planes, the commanding officer, signal codes and—everything! Why, I can hardly believe it! It must have taken his agents months of blastedly clever work to gather all that data!"

The colonel suddenly cut himself off short. A lot of the anger and the red faded from his face, and in the next moment he actually smiled.

"But not too clever, I fancy," he said. "The Nazi is a strange creature. He can make himself perfect in all things except one. I mean that in his make-up there is always one very strong failing. And that's why they never win in the end, because they always make one costly slip. The weak link breaks, you might say, and all the rest goes to pot. In Herr Baron the weak link was his tendency to put details down on paper. As Wilson said, the chap didn't care to trust to memory. Listed here are the names and addresses of every one of his agents in England. He even has listed the contact points that his agents use to get across the Channel to Occupied France."

"You unearthed a gold mine for the colonel, Dave!" Freddy Farmer cried excitedly. "Now British Intelligence can throw out a dragnet and catch every—No?"

Young Farmer checked himself and spoke the last as Dawson made a wry face and shook his head.

"No, Freddy," Dave said sadly. "Unless Herr Baron is a complete dope, which he sure isn't. You're forgetting that the rat got away from us, Freddy. He'll discover that his little book is gone, and the first thing he'll do is to make sure his agents clear out and clear out fast. Am I right, Colonel?"

"I'm afraid you are, Dawson," the senior officer agreed with a heavy sigh. "He'll do just that, unquestionably. Now, if only we had captured him with this little book, then—But we can't expect everything to go in our favor. But let me continue with what is perhaps the most important item in this little black book. This will interest you particularly, Major. There are several references to Number Sixteen Kholerstrasse!"

Major Crandall sat up straight, as though he had been shot.

"No?" he gasped. "You mean—?"

"Exactly, Major," Colonel Fraser interrupted. "Number Sixteen Kholerstrasse in the city of Duisburg, Germany. He has listed here certain dates when his agents are to report to Number Sixteen Kholerstrasse. And the last date, which he has underscored several times, is the twenty-fourth of this month!"

"So the rats are all going back to the same hole!" Major Crandall said softly, as though he couldn't believe his own words. "But—but to tell the truth I've been doing a little thinking about Sixteen Kholerstrasse lately. Four of the mystery factories are located in the Duisburg area. The nerve of those rats! Using the very nest we thought we'd smoked out for keeps. Right now I don't know whether that's being clever, or being damn fools, to tell you the truth."

"It was being blasted clever, until Dawson got hold of this!" Colonel Fraser said, and held up the little black book. "Frankly, I'd never have suspected that they would use the same place again. But that's the Hun for you. They are very likely to do the totally unexpected, ingrained as they are with routine. But they're a queer race, anyway."

"And one the world could well do without!" Dawson said grimly. "But is it permitted to ask questions at this point, sir?"

"Quite," the colonel smiled. "But don't bother, because I'll explain. All this certainly must sound like so much gibberish to you two. Well, Number Sixteen Kholerstrasse, in Duisburg, Germany, was for a long time the Western Germany Headquarters of Himmler's Gestapo, and the German Intelligence, and secret police. The clearing house, you might say, for all of the occupied countries, as well as the British Isles. Well, a few months ago we got wind of its existence. Also word that Himmler himself, and several of his important key men, were going to meet at Number Sixteen—for a little discussion of policy, no doubt. Anyway, it gave us a very bright idea, though the idea failed to turn out one tenth as bright as we had hoped. To make a long story short, we formed a sort of Commando squad of British, American, and Russian agents operating in Germany, plus a few members of the French Underground. The idea was, of course, to storm the place and wipe out Herr Himmler, and several others, and perhaps capture valuable papers and such."

The colonel paused for a moment, and a look of bitterness and sadness came into his eyes.

"The raid was made, but luck was not with us," he presently continued in a low voice. "Something went wrong. Nobody seemed to know just what, or why. But it appeared that the Huns had been tipped off. Neither Himmler nor his key men were there at the time of the raid. Our men killed a few of the lesser lights that were present. But five of our men died, and not one slip of paper of any value was obtained. Hand grenades and rifle fire made a mess of the place, so the report stated. But that's about all the raiding party accomplished. It was just another one of those rotten bits of luck that couldn't be helped. Like the time the Commandos raided Marshall Rommel's Headquarters in Libya, only to find that the Desert Fox had flown to Germany the day before for a meeting with Hitler. No, we are not very proud of the Sixteen Kholerstrasse affair. The Hun beat us at every turn that time. And now the beggars are obviously using it again. That is indeed interesting."

"And four of those mysterious factories are in the Duisburg area," Major Crandall murmured. "Don't forget that, sir. I'd like to make a bet that Number Sixteen is the nerve center of whatever the Nazis are cooking up for us."

"And I wouldn't take that bet, Major, because I quite agree with you," Colonel Fraser said firmly. "And here's one more thing. Not only has Herr Baron underscored the date when the last agent is to report to Number Sixteen, he has also referred to it as Der Tag. The big day for whatever it is they are preparing."

"And it will be a blow against the combined American and British air forces in England," Freddy Farmer murmured. "Unless, sir, there's more in the little black book than you've told us?"

Everybody looked at young Farmer in puzzled surprise.

"What's that?" Colonel Fraser echoed. Then, with a shake of his head, "No, there's nothing else here. Just his agents, the dates they are to report to Duisburg, and the data on our air forces in England. But what makes you think, it's to be a blow against our air forces?"

"A hunch, Dawson would call it, sir," Freddy Farmer replied. Then, leaning forward with a very earnest expression on his face, he continued, "On the face of it, sir. I mean, all his agents are to report to Duisburg at certain dates. Very well, it's obvious that he can't rely on his memory. He has to put details down on paper. In code, true, but still down in black and white. Well, doesn't it strike you that Herr Baron planned to go to Duisburg, too, and that his report will be complete information on our air forces in England that he and his agents have collected? If there is any secret business being prepared for us at Duisburg, doesn't it seem logical that it will ultimately be directed at our air forces? Is there anything that we have that the Nazis would rather smash than our air power? Of course, I may be all wrong to—"

"But you're not all wrong, far from it!" Major Crandall broke in. "I think you've hit the nail right on the head. Now that you've put it that way, a lot of things seem to check. And one item is something that it hurts to mention. It's that I haven't been able to contact a single one of my men posted in the Duisburg area for over a month. I am afraid they're dead. They found out the secret, but paid with their lives before they could get word through to me."

"Farmer must be right!" Colonel Fraser said, tight-lipped, as though he were speaking to himself. "Both Hall and Perkins were to have reported from that area days ago. And there hasn't been a single word from either of them."

Silence settled over the room as the Colonel's words were lost to the echo. Presently Dawson opened his mouth to speak, but seemed to think better of it, and reddened and closed his lips. A few moments later, though, he gave a little stubborn shake of his head.

"Would it help if Farmer and I took a crack at it, sir?" he asked.

Colonel Fraser looked at him in frowning bewilderment.

"A crack at what, Dawson?" he demanded.

Dave hesitated, and his face was fiery red when he spoke.

"Getting to Duisburg, sir," he said slowly, "and trying to find out just what's to happen on the seventeenth of this month."

The colonel blinked, looked just a trifle annoyed, and opened his mouth to speak. However, he changed his mind and smiled faintly.

"I admire your courage, and your splendid offer, Dawson," he said. "But it would be impossible, old man. You just couldn't bring it off, though not through any fault of yours, mind you. But the whole place is double guarded, as Major Crandall explained. And, not to take away one bit from the splendid services you have rendered Intelligence in the past, both the major's men and mine were the very best in the game. They have been there on the spot for weeks, and have obviously failed, and paid with their lives. Heaven knows I'd grab at your offer if I so much as thought there was the ghost of a chance, but—Well, you see, old man?"

The colonel smiled kindly, and gestured with his two hands, palms upward. Then he blinked as Dawson smiled back at him, and shook his head.

"No, sir," he said, "I don't see it your way. I don't mean that Farmer and I would walk right into Number Sixteen Kholerstrasse and find out what was what. Chances are that we might neither of us get to within a mile of the place. However, if those mysterious factories are linked up with Number Sixteen, then maybe we could do something about it. Learn a little something, anyway."

"Eh?" the colonel murmured. "I—I don't quite think I follow you. Do you mean, get a look at what's in those factories? But, good heavens, my dear chap! How on earth—?"

"Something like that, sir," Dawson interrupted quietly. "But not, perhaps, the way your agents, and Major Crandall's agents, tried it. I wouldn't be so conceited as even to begin to think that I could walk in their footsteps and accomplish something they failed at. And I know Farmer isn't that conceited either."

"Oh, definitely not," Freddy said. "But what in the world are you driving at, Dave?"

"Yes, Dawson, speed it up, will you?" Major Crandall said with a frown. "What's it all about?"

Dawson hesitated and drew in a deep breath like a man about to make a high dive into icy water.

"Briefly, this, sir," he finally said. "Two Luftwaffe pilots fighting off an R.A.F.-Eighth Air Force raid on Duisburg are shot down. They bail out and come down close to one of those mystery factories. They seem to be injured, and are probably taken inside the factory to be given first aid. Or maybe they just stumble in like dazed men not knowing where they are going. Anyway, they get inside and they certainly see something of what's going on inside. Well, those two Luftwaffe pilots will be Farmer and myself."

"My word!" Colonel Fraser almost choked, as Dawson paused. "But—but it's too utterly fantastic, Dawson!"

"I don't know, sir," Major Fraser broke in quickly. "Maybe he's got something there. Yes, maybe he has got something there."

"But, my dear Major!" Colonel Fraser exclaimed, and stopped. Then, beginning again, he said, "Assume, if you like, that they can float down by parachute as Luftwaffe pilots. Assume that one of them does get into a factory. What then?"

Major Crandall didn't reply. He looked at Dawson instead.

"Well, what about it?" he asked quietly.

"If we get in as wounded or fight-dazed Luftwaffe pilots," Dawson said with a shrug, "the chances are that we can get out, too. After all, Farmer and I read, write, and speak German. Also, we've been in that part of the world before. Of course, I'm giving just a brief outline of the set-up. It will take some thinking over, and planning. But I sincerely believe we'd stand a fair chance for success. As you well know, after an air raid things are in pretty much of a confused state. During that confusion we might be able to cash in. We might even be able to get a look at this Number Sixteen Kholerstrasse."

"But about getting back to England, Dawson?" Colonel Fraser said, as the look of disbelief began to fade from his eyes. "How would you get back?"

"That would take some thinking over, too, sir," Dawson smiled at him. "But, offhand, I'd say there were a couple of ways that might work. One, a Yank or R.A.F. plane could make a night or early dawn landing at a certain spot near Duisburg at a prearranged time, and take us aboard. Or we might cross the border into one of the Occupied countries and get in touch with the Underground, and have them send us home through the usual channels."

"Or even contact one of my men, if any are left, and let him get you out," Major Crandall murmured, as though to himself. Then, looking at Colonel Fraser, he said, "Dawson is dead right, sir, when he says that it requires a lot of thinking over and planning. But, frankly, I'm convinced more than ever that he really has got something workable. And after all, time is short, and we've got to do something at once. The twenty-fourth is Friday, you know, sir."

The senior officer didn't reply at once. He turned his head and looked at Freddy Farmer.

"What do you think about it?" he asked. "Would you want to go on such a mad mission?"

"Even if I didn't want to, sir, and I most certainly do," Freddy replied, "I'd go along anyway to make sure that Dawson didn't blunder into any trouble."

"I was misunderstood!" Dave cried. "This would be strictly a solo venture. I couldn't possibly meet with success, if I had to carry Farmer around on my back, too!"

Colonel Fraser looked at him, then switched his gaze to Major Crandall's face, and smiled faintly.

"Maybe that is the secret of their past successes, Major," he said. "The ability to pull each other's leg, when actually death is staring them in the face. Well, I suppose that settles it. Only it seems too utterly impossible. It—"

"Just a minute, sir, if I may?" Dawson interrupted. "That job you sent us on in Nineteen Forty was also a parachute over enemy territory job. What did you honestly think of our chances then, sir?"

"Frankly," the senior officer replied gravely, "very slim indeed."

"But we were lucky enough to get back, sir," Dawson said quickly. "So why shouldn't we be just as lucky this time?"

"No reason at all," Colonel Fraser said. "Only you put it wrong when you speak of luck. With you two luck plays only a minor part. Very well, then, let's get down to thinking out this thing, and planning the operation right down to the minutest detail. I have here all the latest maps and Recco plane photographs of that area."

The sun had long since burned through London's early morning overcast when Lieutenant Faintor drove Dawson and Farmer to a hotel and secured rooms for them. He hung around until they had downed a good breakfast and were tucked away in bed. Then he grinned, gave them the V salute and went his way.

"Well, did I win my bet, or did I win my bet, pal?" Dawson yawned, and pulled the covers up around his neck.

"Eh?" Freddy Farmer mumbled. "Oh! That we wouldn't go to Kingston, or back to the Squadron, because the colonel had something in mind for us? Well, you lost it!"

"What do you mean, lost it?" Dave demanded.

"Quite!" Freddy said sleepily. "It was you who had something cooking for us, not the colonel. And now that we're alone, old thing, let me say that you are definitely mad, and absolutely balmy. But I'm quite used to that side of you by now. So don't feel hurt. And go to sleep, will you?"

Maybe it was intentional, or maybe not, but the comment Freddy Farmer received on his words was a gentle snore.