“It’s strange and old and mysterious,” said Berta, half to herself. “It’s asleep and dreaming of the old days when people lived here. It doesn’t like us being here!”

“Wake up!” said Dick. “You look quite dopey!” Berta shook herself and looked round again. Then she went on through the castle and looked at other rooms, some without roofs, some without one or two of their walls.

“It’s a honey of a castle!” she said to George. “A real honey. Wunnerful. WonDERful.”

They wandered all round, showing the awe-struck Berta everything. “We’ll show you the dungeons too,” said George, very pleased to be impressing Berta so much.

“Dungeons! You’ve got dungeons too — oh, of course, you told me about them,” said Berta. “Dungeons! You don’t say! My, my, I’ll never forget this afternoon.”

As they walked over the old courtyard Timmy suddenly growled and stood still, his tail down, the hackles on his neck rising. Everyone automatically stood still too.

“What is it, Tim?” asked George, in a whisper. Timmy’s nose was pointing towards the little harbour where they had left their boat.

“There must be someone there,” said Dick. “Don’t say they’re going off with our boat!”

George gave a scream. Her boat! Her precious boat! She set off at top speed with Timmy bounding in front.

“Come back, George — there may be danger!” shouted Julian, but George didn’t listen. She ran over the rocks that led down to the little harbour-beach, and then stopped still in surprise.

Two policemen were walking up the sandy beach! Their boat was drawn up beside George’s. They saluted her and grinned.

“Afternoon, Miss George!”

“What are you doing on my island?” demanded George, recognising them. “Why have you come here?”

“Someone reported suspicious people on the island,” said the first policeman.

“Who did?” said George. “Nobody knew about it but us!”

“I bet I know who reported it,” said Dick, suddenly. “Joan did! She didn’t like us going off by ourselves, she said we ought to telephone the police.”

“That’s right,” said the policeman. “So we came to see for ourselves. Found anyone?”

Julian took command then, and related how they had first seen the cigarette ends, and then heard the motor-boat starting up, and had gone to see it roaring away from the island.

“Ah,” said both policemen, profoundly. “Ah!”

“What do you mean—‘AH?’ ” asked Dick.

“Fred here heard a motor-boat somewhere in the bay in the night,” said the first man. “What was it doing there, I’d like to know?”

“So would we,” said Julian. “We saw someone on the island looking through binoculars at the beach this morning.”

This brought forth two more “Ahs,” and the policemen exchanged glances.

“Good thing you’ve got a couple of dogs with you,” said the one called Fred. “Well — we’ll just have a bit of a look round, and then we’ll go back on our beats again. And mind you ring us up next time anything turns up, Miss George, see?”