The children made their way to where the boat was tied to a tree. It was now piled with sweet-smelling bracken. Jack had taken up the seats, so that the whole of the boat was a bed. The two girls got in and cuddled down, and then the three boys settled themselves too. It was a bit of a squeeze, but nobody minded. They wrapped the two old rugs round them and talked quietly.

The lake-water lapped gently against the boat, saying “lip-lip-lip” all the time. It was a pleasant sound to hear. An owl hooted in a trembling voice not far off. “Ooooooooo! Oo-oo-oo-oo!”

Paul sat up in a fright. “Who’s that?” he said.

Mike pulled him down. “It’s only a bird called an owl, silly!” he said. “Don’t sit up suddenly like that, Paul, you pull the rug off us.”

Paul lay down again and cuddled up to the other two boys. He was glad that the noise was only made by a bird.

The moon came up soon, and shone down through the black branches of the trees above. The water of the lake turned to silver. “Lip-lip-lip” it said all the time against the boat. Nora listened to it and fell asleep. Peggy lay on her back and looked at a star that shone through the trees, and suddenly fell asleep too. Paul was soon asleep, but Mike and Jack talked quietly for some time.

They couldn’t imagine what Mr. Diaz and Luiz were going to do next. If they stayed long on the island the children couldn’t go back there - and as they had no food, this was serious. On the other hand, if they tried to make their way through the thick woods nearby, they might get quite lost.

“If only we could make Mr. Diaz and Luiz prisoners, just as they made you and Paul, it would be grand,” said Jack. “Then we could do what we liked.”

Mike lay silent for a moment - then he made such a peculiar noise that he really frightened Jack.

“Mike! What’s up?” said Jack in alarm. “Are you ill?”

“No,” said Mike in a very excited voice. “It was only that I suddenly got such a marvellous idea I wanted to shout - and I only just stopped the shout in time. That was the funny noise you heard - me stopping the shout. But oh, Jack, I’ve really got the most wonderful idea!”

“What is it?” asked Jack in surprise.

“Well, it was you saying that you wished we could make Mr. Diaz and Luiz prisoners that really gave me the idea,” said Mike. “I know how we could! If we could only get their boat away from the island to-night, they wouldn’t be able to leave - and they’d be prisoners there!”

“Mike! That’s a most marvellous idea!” said Jack. “It solves all our difficulties. You really are a clever chap! Once they are prisoners on the island, we can row to the village at the end of the lake, get a car, and go back to Peep-Hole in safety!”

“Yes,” said Mike, trembling with excitement. “How shall we do it. Jack?”

“Wait a minute,” said Jack, frowning in the moonlight. “I’ve just thought of something. Suppose Mr. Diaz and Luiz can swim? They could easily swim across to the mainland and escape that way.”

“But they can’t swim,” said Mike. “I heard Luiz tell Mr. Diaz he couldn’t, and Mr. Diaz said he couldn’t either. It was when I was a prisoner up in the tower - they often used to come and sit with us there, and they talked to one another. So if neither of them can swim they really would be prisoners!”

Jack was so delighted the he wanted to sing and dance. He carefully took off his share of the rug and put it over the sleeping Paul.

“We needn’t wake Paul or the girls,” he said. “We will undress, Mike, then slip into the water over the edge of the boat, and swim to the island. You can swim as far as that, can’t you?”

“Easily,” said Mike. “Then we’ll undo their boat get into it and row off! Oh, Jack, this is the most exciting thing we’ve ever done! I wonder if they’ll see us!”

“I don’t expect so,” said Jack. “They’ll be asleep in our cave, I expect!”

The boys undressed without waking the girls or Paul.

They slid into the water over the side of the boat and swam off in the moonlit lake, only their two dark heads showing on the calm, silvery surface.

It was rather farther to the island than they expected. Mike was tired when they reached the men’s boat, but Jack, who was a marvellous swimmer, was quite fresh. He got in and pulled Mike in too. He undid the rope that tied the boat to a tree.

Then he pushed off, the oars making a splashing noise in the silence of the night. No sooner had they gone a little way out on the lake than a shout came from the island, and Luiz stood up. He had been asleep on some heather, and had awakened to hear the sound of oars.

“Hie! That’s our boat you’ve got! Bring it back at once!”

“We’ll bring it back some day!” yelled back Jack in delight.

“You just bring it back now, at once!” yelled Luiz, suddenly realising that he and Mr. Diaz would not be able to leave the island at all without a boat. “You wicked boys!”

“Good-bye, dear friends,” shouted Jack, seeing Mr. Diaz suddenly appearing down the hill. He had been sleeping in the cave and had awakened at the noise of shouting. “See you some day soon!”

The two men were quite helpless. They could neither of them swim, they had no boat - they could do nothing but shout angrily, and that was no good at all! The boys simply laughed and waved to them.

When they reached their own boat, feeling rather cold and shivery, for they had no clothes on, they found the girls and Paul wide awake and rather scared. Peggy threw the boys their clothes, and called out to know where they had been and what all the noise was and where they had got the other boat.

“Can’t you guess!” cried Nora. “They’ve taken the enemies’ boat - and now they are prisoners on our secret island, hurrah! Oh, Jack, what a marvellous idea! We were so scared when we woke up and found you two gone - but we might have guessed you were off on some wonderful idea!”

“It’s Mike’s idea,” said Jack, dressing quickly. “It’s one of the best ideas he’s ever had! It acted beautifully too - Mr. Diaz and Luiz are as angry as can be, but they can’t do anything about it! As soon as it’s light we’ll row to the village at the end of the lake, get a car, and go off to Peep-Hole to see what Dimmy and George have done - and Mr. Diaz and Luiz can have a nice little holiday on the island!”

Everybody laughed. They felt sure they would never be able to go to sleep again that night, but after a while they began to yawn - and before the moon had begun to slide down the sky they were all fast asleep once more, with Mr. Diaz’s boat tied safely alongside their own.

They woke when the stars had gone and the moon had slipped away. The sun was coming up in the east and the lake looked peaceful and blue. Not a cloud was in the sky.

“Goodness, I am hungry!” said Peggy. “And we haven’t got a single thing to eat!”

Mike grinned. He put his hand into his pocket and brought out a large packet of chocolate!

“I kept this till this morning, thinking it would come in very useful!” he said. “We’ll share it, and then we’ll have to wait till we get to the village at the end of the lake for breakfast.”

“Good old Mike!” said every one, delighted to see the chocolate. It had nuts in it and was most delicious. They sat in the early morning sunshine, munching it and giggling whenever they thought of Mr. Diaz and Luiz!

“There they are, at the edge of the lake, trying to see us!” said Peggy. “Well, they’ll see us soon enough when we row out! What shall we do with their boat, Jack?”

“We’ll leave it tied up here,” said Jack. “It will be safe enough.”

So they left the extra boat behind, untied theirs, and rowed out on to the lake. Mr. Diaz and Luiz saw them at once, and shouted, but the children took no notice at all. They rowed steadily away from the island down to the village at the end of the lake.