"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?"