The shrill whistle of the locomotive echoed across the twilight-steeped English countryside. The train lurched and trembled for a moment or so, and then started gliding smoothly along the tracks. Dave and Freddy took a last glance out the compartment window at the Chelmsford station and then settled back comfortably on the cushioned seats. They had the compartment to themselves, and for that they were truly grateful. They were headed for London for half leave and half military reasons, but that didn't mean they weren't tired. The last few weeks had been crowded with more aerial warfare than had taken place in a whole year in World War Number One. The Royal Air Force had almost single-handed held back the Nazis from crossing the Channel. Still outnumbered, but not so much as at Dunkirk, the R.A.F. boys from the squadron leaders right down to the lowest grade mechanics had gained mastery of the air over the Channel and over England. And, what was more important, they had held that mastery regardless of the German fleets of planes Goering had hurled against them.

Stretching out, Dave leaned his head back, and cocked his feet up on the opposite seat.

"If I could only get Air Vice-Marshal Saunders off my mind," he sighed, "I might catch me a bit of shut-eye. Boy, we've been hitting that old ball lately, you know?"

"Hitting what?" Freddy murmured, and closed his eyes. "What in the world does that mean?"

"Sure, hitting the old ball," Dave said lazily. "Smacking that apple. Hitting on all six. Right on the beam every minute. Catch on?"

"Oh, of course!" Freddy groaned, and gave a shake of his head. "A chap who spoke English would certainly be at a loss in the States, wouldn't he?"

"That's right," Dave said sleepily. "Just like an American being in England. Lift, for elevator! Treacle, when it's syrup! Queue-up, when you mean standing in line. Boy, what a language! And, am I all in! Jeepers! Am I tired! Am I—"

The sudden and abrupt slackening of the train's speed woke both boys up in a flash. In fact, it woke them up in the dark, for it was late evening outside, and while they had dozed the conductor had come in and pulled down the compartment window curtains. A very pale blue light in the corridor outside was of no more good than no light at all.

Freddy groaned aloud, flexed his stiff muscles, and peered around a corner of the window curtain.

"Now what?" he murmured. "Dark as pitch outside, but I'm sure we're not even close to London yet. I say, hear those anti-aircraft guns?"

"With both ears," Dave said, and took a squint out himself.

By pressing close to the glass and trying to look in the direction of the engine, he could just barely see the long pencil-thin beams of searchlights raking the heavens far ahead. And every now and then the dark sky was stabbed by blotches of flaming red and crimson.

"The Jerries are over again, trying to hit some more women and children," he said grimly. "I hope our night boys get every darn one of them."

"They'll get some, I fancy," Freddy said quietly. "But why are we running so slow? That raid is miles and miles ahead of us. Besides, I always thought a moving target was much harder to hit. This blasted train might just as well go sixty miles as six, as it must be doing now."

"Stay after school, Pilot Officer Farmer!" Dave snorted. "And here I thought you knew all the answers! My, my!"

"Oh, come off it!" Freddy snapped. "I suppose you know the reason?"

"Sure," Dave said.

"Well, what is it?"

"An official secret," Dave said in a hoarse whisper. "I'd tell you, but how do I know there isn't a Nazi agent under the seat?"

"You'll be under the seat, if you don't cut it out!" Freddy whispered back at him. "Now, what's the great reason?"

"Okay, if you've got to know," Dave said in a patient, resigned voice. "This is how it is, my little man. German planes carry bombs, and when they get over here they drop those bombs, see? Well, one might drop on the track way ahead of a train going sixty miles an hour, see? Well, maybe the engineer couldn't stop in time, and the train would pile up. But if the train crawls along until the all-clear is sounded, then the engineer can stop it on a dime if he should go around a curve and suddenly see a nice big bomb crater where the tracks should be. Now, right or wrong?"

Freddy made clucking sounds with his tongue in the darkness.

"Why, I believe the chap is right," he said, as though talking to himself. "Yes, I fancy he has a little bit of something useful between those big ears of his. You are right, of course, Dave."

"Ever see me when I was wrong?" Dave taunted. Then quickly: "No, let's not bring that up! Hey! Those planes are headed this way!"

Dave could have saved his breath on the last. As though a huge invisible door in the sky had been opened, the thunder of the guns tripled in sound. The compartment was suddenly bathed in the pale reflection of a battery of searchlight beams that suddenly sprang into action less than fifty yards from the tracks. The train had come to a full halt now, with its headlight turned off. A moment later came the familiar drone of night-bombing Heinkels and Benz-Daimler powered Focke-Wulf 187s above the roar of the batteries of anti-aircraft guns.

For a moment Dave and Freddy watched the approach of the raiding planes. Then common sense got the best of curiosity. They stretched out on the compartment floor beside each other to protect themselves as much as possible in case any of those eggs of death should happen to land near the train. Perhaps they looked funny huddling down on the compartment floor in their best Sunday-go-to-meeting uniforms. However, in England it is not a sign of being afraid or of cowardice to fling yourself flat when the bombers come over. It is a sign of good sense. Perhaps it is true that the bomb or bullet that gets you has your name on it, and you can't escape it no matter where you are. At the same time, though, only a fool or a madman deliberately dares a bomb to do him harm.

And so Freddy and Dave hugged the floor while the raiders roared over and plastered the countryside with their loads of death and destruction. At least fifty times an earth-shaking roar, and a towering sheet of flame, made them think that was the last bomb they'd ever hear in this war, or in this world. Each time invisible hands seemed to reach down out of that roaring, flame-filled night sky and lift the train clear up off the tracks, and then let it drop back with a jarring crash. After each outburst, however, they continued to remain alive. And presently the throbbing drone died away in the distance, the roaring and barking of the guns ceased, and the searchlight beams winked out one by one. Night returned again to that section of England—night painted here and there with the glow of fires set by the bombs.

"The big bums!" Dave growled, and got up off the floor. "As if you and I haven't got enough to worry about without them buzzing over to make things worse. Were you scared, Freddy?"

"Stiff," the English youth promptly replied.

"Me, too," Dave said with half a chuckle. "That's my knees you hear, still knocking together. And they say you get used to air raids. Oh boy!"

"You probably do," Freddy said. "But I have no desire to prove it to myself. I hope the blighters didn't hit the track. It's a long walk from here to London. I say, what's that?"

At that moment a burst of shots had shattered the comparative silence outside. Regardless of regulations, the boys threw up their compartment window and leaned out. They saw a figure stumbling through the shadows alongside the train. He was bent over double as though in pain, and his footsteps faltered. Just as he came abreast of their compartment some more shots rang out. The stumbling figure stumbled for the last time. He fell forward, flat on his face, and lay still. In a few seconds half a dozen men in uniform came rushing up. One of them flashed a light on the still figure, then bent down and rolled him over.

"Well, that's one blighter they won't be able to count on from now on!" a voice growled. "A jolly good thing he's finished, too!"

"Right!" a second voice said. "If we hadn't been a patrol, it might have turned out a mess for this train. Fancy the beggar trying to let them know where it was!"

"I say there!" Freddy called, and leaned farther out the window. "What's all this?"

"Keep back in that train, and—!" a voice started to say, but stopped as the flashlight beam caught Dave and Freddy for a second in its glow. "Oh, sorry, sir," the same voice spoke again. "Thought you were just nosy civilians, not R.A.F. Well, sir, we caught another one of them Fifth Column beggars trying to do us harm."

"Yes, sir; that's right, sir," another voice broke in. "We were on our usual patrol along the track when suddenly we saw some bloke slinking along ahead of us. The raiders weren't even close, then, so we just followed this beggar and didn't challenge him. Well, strike me pink, sir, if he didn't drop down on the tracks, and whip one of them red flare things from his pocket and start to light it."

"But he didn't get away with it, I can tell you, sir," the first voice spoke up. "Me and Harry, here, right ups and jumps on him before he's even got the match to it. But he's a strong one, and he gives us a bit of a fight, and—"

"A bit of a fight?" the other voice interrupted again. "The blighter tosses us around like we're a couple of rag dolls, and starts scooting down the track. By then the bombers are right over us, and—Well, I guess you heard the things they dropped. Anyway, we lose this blighter for a bit during the mess-up. Then we spot him trying to get on the train. We don't bother to challenge, now. We just let him have what he deserves. And here he is. A good thing, too!"

"A very good thing," Freddy added. "Congratulations. You're air raid wardens, aren't you?"

"That's right, sir," one of them replied. "Too old for any regular military work, but we're jolly well glad to do what we can to help."

Dave looked down at the still figure on the ground. But for the watchfulness and constant vigilance of those "old" men, that dead Nazi spy might have lighted the signal flare on the track and made it possible for the German bombers overhead to see the slow moving train. But for those "old" men a bomb might have come screaming down to strike the train and blow one Dave Dawson and one Freddy Farmer straight into the next world. Dave glanced up at the men, and his eyes glowed with frank and open admiration.

"And without your help," he said, "England would be in a pretty tough spot. She can thank you fellows for a lot—and how!"

The air raid wardens chuckled in an embarrassed sort of way.

"Well, thank you, sir," one of them said. "It's mighty nice of you to put it that way. We're glad to do our bit, though. You sound like a Yank, sir."

"Oh, don't mind that," Freddy spoke up with a laugh before Dave could say a word. "You'd be surprised how he mangled the language at first. But he's really doing awfully well—for a little fellow. The squadron commander's going to let him taste his first cup of tea next week. And—Ouch!"

Dave had eased off the window catch so that it slid down on Freddy's neck. He held it there with his hands and grinned at the air raid wardens through the glass. They roared with laughter. Then as the train started to move, Dave released Freddy's neck and pushed the window up.

"Good luck!" he shouted, and leaned out. "Thumbs up, mates!"

"The same to you, sir!" they shouted back. "Thumbs up, R.A.F.!"

The train picked up speed, and another little incident in the war careers of Dave Dawson and Freddy Farmer became history. They closed the window, pulled the curtain down, and sank back on the seats. Freddy rubbed the back of his neck and glared at Dave's grinning face.

"Go ahead and grin, you queer-looking ape," he muttered. "But I'll get back at you, no fear. And when I do, you'll jolly well know it, too."

"Let that be a lesson to you to speak of your superiors in the future with more respect," Dave chuckled. "You're lucky, my little man, I didn't make you keep your head hanging out there all the way to London. But, gee, you English are certainly swell people!"

"Naturally," Freddy said in mock gravity. "Look who we are, my dear fellow. And just think how fortunate you are to have the opportunity to observe and learn."

"No kidding, though," Dave said, "Hitler just hasn't a chance. It gave me a great kick to meet those air raid wardens back there."

"I know what you mean," Freddy said, and nodded. "It isn't just the Army, and the Navy, and the Air Force fighting Hitler, now. It's England—all of England from the oldest right down to the youngest."

"What a dope Hitler was even to think he could get away with it!" Dave murmured. "Boy, oh boy! Is that guy riding for one big fall!"

"And I jolly well hope it will be soon!" Freddy echoed. "And that reminds me. I certainly wish I knew what Air Vice-Marshal Saunders wants of us!"

Dave groaned and slid down on the seat.

"My pal!" he sighed unhappily. "Just when I was all nice and relaxed, you'd have to go and bring that up!"