The four children made their way to the high rocky ledge. Andy made them lie down flat and wriggle like Red Indians as they reached it.
"Better not let ourselves be seen, if anyone is down there," he whispered. So, as flat as snakes, they wormed their way to the rocky ledge—and when they got there, they had the biggest surprise of their lives!
In the quiet water that lay outside the second island was a large and powerful seaplane!
Yes—a great seaplane, whose wings spread widely over the blue water. No small motor-boat purred there. It was the seaplane's engine that Andy had heard so mysteriously in the middle of the night.
"Whew! Look at that!" whispered Andy, his face going as red as a beetroot with excitement. "I never thought of a seaplane! What a very extraordinary thing!"
"Let's get up and shout and wave." begged Jill. "I'm sure they will love to rescue us."
"Haven't you seen the sign on the wings?" asked Tom, in a curiously angry voice. The girls looked. The sign of the crooked cross was painted on each wing—the sign of the enemy, the foe of half the world.
"Golly!" said Mary, and she drew a deep breath. "Enemies I Using these islands! Do they belong to them?"
"Of course not," said Andy. "But they are desolate, and out of the usual ships' course—and they've been noted by the enemy, and he's using them as a kind of base for something—seaplanes perhaps."
"Well—what are we going to do?" asked Tom.
"We shall have to think," said Andy. "One thing is certain. We won't show ourselves tell we've found out a fitted more. We don't want to be taken prisoner."
"That's what that food was for, then—the people who come here," said Jill. "I suppose the seaplanes come over here for food and petrol. Ifs a good idea. How I wish we could get away and tell my father about it—he'd know what to do. I guess he'd clean up this place, whatever it's used for!"
"I say—hadn't we better take down our signal whilst that seaplane is here?" asked Jill. "If it happens to see it, the enemy will know there are people on this island". And" what about the fishing-boat? That might be seen too."
"I don't think so," said Andy. "It's well hidden between those rocks. But the signal had certainly better come down. We won't put it up any more. Come on. Tom—we'll take it down now."
"We'll come with you," said the girls. But Andy shook his head.
"No," he said "From now oh, somebody must keep a watch on that seaplane. We must find out all we can. We will be back with you as soon as possible—but you must stay here and watch."
So the two girls were left behind whilst the boys ran across the island to take down their flapping signal.
"I don't know where in the world we should hide if we were discovered and hunted for," said Andy, rolling up the sail. "There isn't a single place here to hide away in—not a cave or anything."
Tom felt rather uncomfortable. He didn't want to be hunted for on that bare island! "I wish we could see how many men there are in that seaplane," he said, "and what they are doing, and everything."
"Where are your field-glasses?" asked Andy suddenly. "They would be just the thing to use. We could see everything as dearly as could be, then!"
"And my camera, too!" said Tom, jumping for joy. "What about my camera? We could take some photographs of the seaplane—then everyone would have to believe us when we get back—if ever we do get back!"
"That's a fine idea!" said Andy, really pleased. "Golly! If we could take some pictures of that seaplane with the crooked cross showing up clearly, there wouldn't be the least doubt of our story when we got home. Tom, let's go and get your glasses and your camera straight away."
They dumped the sail into a bush and ran to the shack. They took Tom's field-glasses and picked up the camera to see if it needed a new film. No—there was a new one inside.
"Better not use up all the film on the seaplane," said Andy. "There might be other interesting and extraordinary things to photograph—you never know!"
"Oh, I've got three or four films," said Tom. "I brought plenty with me, thinking I was going to get some good bird pictures, you know. Come on-let's go back to the girls and see what they have to report."
The girls were very glad indeed to see the boys. They had a lot to tell.
"Andy! Tom! As soon as you had gone the men in the seaplane put out a funny little round sort of boat," said Jill in excitement. "And they paddled to shore in it, and went to our cave. What a good thing the sea had washed away all our footprints!"
"It was, indeed," said Andy. "Tom, give me the field-glasses. I want to have a look through them."
Andy stared through the powerful glasses. They were so strong that they seemed to bring the seaplane near enough to touch! The boy saw the great crooked crosses boldly painted on the wings. He saw the little rubber boat left bobbing in the surf, whilst the men visited the cave—either to take something to it, or to bring something away, Andy did not know which.
"There seems to be someone in the seaplane," said Andy. "And, look—there are some men coming from the cave!"
Andy could see them very clearly through his field-glasses—and the others could see them too, though not so well, of course. To them the men looked like faraway dolls.
"They've gone to get food from the cave," said Andy in excitement. "And I guess there's a store of petrol somewhere else for them to get when they want to. Food—and petrol—just what I thought! Using these islands saves enemy planes from having to go hundreds of miles to their own country's stores. My word—we have stumbled on to something queer!"
The men entered their rubber boat and rowed back to the seaplane. Twice more they went to the cave and back. Then they climbed up into the plane and disappeared.
"I'm getting most awfully hungry," said Tom at last. "Can't we go and get something to eat?"
"I'll stay here and keep watch, and you and the girls can go and get your dinner," said Andy. "Don't light a fire, whatever you do—the enemy will see the smoke. Use the stove if you want to cook anything. Bring me something to eat and drink later."
"Right," said Tom, and he and the girls wriggled off the high ledge. They stood upright as soon as they were out of sight of the seaplane and tore to their shack.
They ate a hurried meal, and did not cook anything at all. They made up a dinner-packet for Andy and set off to take it to him.
But half-way there they heard a noise. R-r-r-r-r-r-r-r-r! R-r-r-r-r-r-r-r! R-r-r-r-r-r-r! They stopped at once and listened.
"It's the seaplane going off!" cried Tom—and then the sound came again, more loudly than ever. R-R-R-R-R-R-R.
"Look—it's there!" cried Jill. "Drop flat to the ground or we'll be seen!"
Jill had seen the seaplane just rising into the air over the cliff. The three children dropped flat to the ground and lay there perfectly still. The seaplane roared over their island, rose higher and higher, and at last was nothing but a speck in the sky.
"What a narrow escape!" said Tom, sitting up and wiping his forehead. "Golly! My heart did go bump I I've split the water I was carrying for Andy. I'll have to get some more!"
"It was a shock to see that enormous plane coming!" said Jill. "Oh dear—if we have many more shocks, my hair will turn grey!"
Chapter 10
And Now for the Third Island!
The children were very glad that the seaplane had gone. "It's a jolly good thing our signal was taken down before it flew over the island," said Andy, eating the food that the others had brought to him. "I couldn't warn you. It started up its engine all of a sudden, taxied over the smooth water there, and then rose into the air."