"Yes, sir," Dawson spoke for the two of them. And then after a split second's hesitation, he added, "May I ask why, sir? I mean, has something unexpected happened?"

"Not exactly," the voice at the other end of the wire said. "It's simply that I don't want anything unexpected _to_ happen. The other one we were hunting down here has turned up. At least it would seem that he has. It was reported to me just ten minutes ago that one of our planes was stolen shortly after you two took off last night."

"A plane swiped?" Dawson blurted out before he could check himself.

"What do you mean, sir? Who stole it?"

"Positive identification was not made," the vice-admiral replied. "But the guard, who was wounded, gives a description that might be our man.

He was shot through the neck by a man in civilian clothes. The light was bad, of course, and the guard didn't have the chance to get a good look at his a.s.sailant, but he says he could be either Mexican, or j.a.p. And of course he was j.a.p. _The_ j.a.p!"

"And you mean, sir, you think he's shadowed us up here?" Dawson asked.

"Quite probable," was the instant reply. "He could land his stolen plane any number of places up there, and not be seen, and make his way to your field on foot. Of course, it may not be that way at all, but we can't take any chances that it isn't. So get going, you two. Get your plane away from there at once, and good luck."

"Yes, sir, and thank you, sir," Dave murmured, and hung up the receiver.

He turned his head and looked at Freddy Farmer's wide eyes, and tried to smile, but it wasn't very much of an effort.

"Well, what do you know?" he breathed. "If it is that rat, then he's a pilot, and he's catching our smoke. Gives you a funny kind of feeling, doesn't it?"

"Quite!" Freddy Farmer grunted, and ran a tongue across his lips. "Makes a chap feel like the witness of a murder, and the murderer still at large, and hunting you down so's you'll never be able to tell."

"Yeah, something like that," Dawson nodded with a shaky little laugh.

"But I wonder, though. I mean, we've been here quite a spell, and we haven't bothered looking behind us. _If_ he's here, and has his gun, he's certainly had a lot of chances to let us both have it in the back.

I wonder why not?"

"Well, stop wondering!" Freddy Farmer muttered, and got to his feet.

"Let's do as the vice-admiral orders, and get away from this place."

"But fast!" Dave echoed with a grim nod. "Suddenly I've had all I want of California for a spell, anyway!"

CHAPTER SIX

_Invisible Killer_

With its four engines singing a song of power that would be sweet music to the ears of any pilot the Flying Fortress thundered its way southwestward through the night-darkened Pacific sky. The aircraft was on the automatic pilot, and both Dawson and Freddy Farmer sat outwardly relaxed at the controls, but inwardly on the alert for the slightest miss in any of the engines, or for anything that would indicate that all was not as it should be. The Los Angeles Air Forces base was six hours behind them. Another six and they should be over Hickam Field, on Oahu Island, waiting for the permission signal to land.

Suddenly, with a little chuckle, Dawson broke the silence that had existed for some minutes between them. Freddy Farmer glanced across at him with a questioning frown.

"What now, Dave?" he asked.

"Us," Dawson replied, and chuckled again. "I guess we're getting old, Freddy. I mean, we seem to scare pretty easy these days. And I'll admit that I was as jittery as a hen on a hot stove until we got this Fortress off the ground, and into the air. I actually had little chills running up and down my back, as though I expected to feel a nice white-hot bullet cut into it at most any second. But heck! Not a thing happened. I didn't see a thing that looked j.a.p, did you?"

"No, I didn't," Freddy Farmer replied. "But my imagination certainly gave me a lot of trouble. Every time one of those mechanics put a bag of mail aboard, or a case of those medical supplies we're taking over, I had a brief moment of feeling positive that he was a j.a.prat, buck teeth, and all. But, as you say, nothing happened."

"Yeah," Dawson murmured, and peered out at the wall of night darkness that completely circled the aircraft. "Just another airplane ride for us. And that doesn't make me mad at all. I wonder if the field radioed Dago when we got off? Vice-Admiral Carter sure sounded plenty worried on that phone."

"Yes, he ..." Freddy Farmer said, and then cut himself off short.

"What's the matter, Freddy?" Dawson asked, as a sudden clammy sensation rippled through his chest.

"Down there," young Farmer replied, and pointed off and down to the left. "Is that a light blinking, or am I seeing things?"

Dawson leaned forward slightly and stared in the direction of Freddy's pointing finger. A couple of seconds later he saw the unmistakable flashing of a light. Because of the Flying Fortress's alt.i.tude it was no more than a pin-p.r.i.c.k of light. But it was very real just the same.

"Yes, I catch," he finally grunted. "Probably one of our ships requesting us to flash our identification signal. The heck with them.

They should know that no j.a.p plane could possibly be in this neck of the woods."

"But what if they open fire, if they have flak guns aboard?" Freddy murmured as they both continued to watch the blinking light far below.

"There's such a thing as a lucky hit, even at our alt.i.tude."

"Okay, if you insist, pal," Dave grunted, and started to reach out his hand. "But ... Hey! Did you catch that, Freddy? That looked like the old SOS to me."

"It was!" young Farmer replied with a nod, and hunched forward a bit more on his co-pilot seat. "Wait a minute! He's trying to send something else. K ... D ... J? K, D, J? Wonder what that means?"

"Take a look in that signal book in the pocket beside you," Dawson said.

"I think those things have surface ship signals as well as aircraft signals. Take a look anyway."

It didn't take young Farmer more than a few seconds to find what he was hunting for. Excitement rang in his voice as he spoke to Dawson.

"Here it is, Dave!", he cried. "K, D, J. Attacked by enemy force! Please give a.s.sistance."

"Attacked by enemy force?" Dawson echoed sharply, and squinted hard down at the still blinking pin-point of light. "Must be some ship nailed by a j.a.p submarine. Maybe we'd better slide down for a look. At least that should scare the j.a.p sub away, if there's one still lurking around. A j.a.p submarine east of Pearl Harbor? Well, what do you know? Get back at the port gun slot, Freddy, just in case we get the chance to take a crack at something. And I think I'll drop a flare so's we can get a good look."

"No, don't, Dave!" young Farmer said sharply, and gripped his arm as though to restrain him.

"No?" Dawson echoed. "Why not? We won't be able to see much in this dark. And certainly not a j.a.p submarine, if there's one on the surface."

"I know," Freddy said with a shrug. "But I've got a funny feeling. A flare would light us up nicely, too, you see? Let's play it cautious, what say?"

"Okay, okay," Dave said with a grin. "Maybe you have got something there. Anyway, get back to the port gun slot, and I'll slide us down a bit."

"Right you are," Freddy said, and slid out of the co-pilot's seat and made his way aft.

Dawson had already throttled the four engines, and was sending the Flying Fortress sliding down through the Pacific night sky in a series of ever widening circles. He circled to port so that he could continually keep his eye on the blinking light that grew bigger and bigger as the Fortress lost alt.i.tude. And the light kept on sending two sets of letters. The standard SOS and KDJ. A couple of times Dawson was tempted to signal back that they had caught the signals and were coming down to find out what they could do to help. Each time, though, something seemed to stop him from showing the bomber's signal light. He had even switched off the c.o.c.kpit light, and he was not allowing the engines to show any exhaust plumes that might reveal the Fortress' exact position.

"Guess I must be as jumpy as Freddy!" he grunted to himself. "But maybe it is best to play it safe, even if it must be one of our surface ships down there. There's no telling what can happen next in this c.o.c.keyed world. And, boy, Freddy and I should sure know that by now. Yeah! So we'll sneak down and only let them know where we are by what sounds of our engines they can catch."

With a nod for emphasis, he flipped up the switch of the Fortress'

inter-com system, and put his lips to the mike.

"Have you hooked this thing up at your end, Freddy?" he asked into what he guessed was a dead wire.

But he was wrong. Young Farmer's voice was in his earphones instantly.

"Yes, Dave. Can you see anything yet, besides the signal flashes?"