Dick flashed his torch round to see if he could spot anything else. He gave a sudden exclamation, and kept his torch fixed on a corner of the room.

“What is it?” said Julian.

“Paper — red and blue silver paper,” said Dick. “Chocolate wrapping! How many times have we bought this kind of chocolate, wrapped in silver paper patterned with red and blue!”

He picked it up and straightened it out. Yes — there was the name of the chocolate firm on it!

Everyone was silent. This could only mean one thing. Someone had been in this room lately — someone who ate chocolate — someone who had thrown down the wrapping never expecting it to be found!

“Well,” said Julian, breaking the silence. “This is surprising. Someone else knows this way in. Where does it lead to? Up to that tower, I imagine!”

“Hadn’t we better be careful?” said Dick, lowering his voice. “I mean — whoever was here might quite well be wandering about somewhere near.”

“Yes. Perhaps we’d better go back,” said Julian, thinking of the girls.

“No,” said George, in a fierce whisper. “Let’s go on. We can be very cautious.”

A passage led from the strange hidden room. It went along on the level for a little way, and then they arrived at a spiral stairway that ran straight upwards like a corkscrew.

At the top they came to a small, very narrow door. It had a great, old-fashioned iron ring for a handle.

Julian stood hesitating. Should he open it or not? He stood for half a minute, trying to make up his mind. He whispered back to the others. “I’ve come to a little door. Shall I open it?”

“Yes,” came back the answering whispers. Julian cautiously took hold of the iron ring. He turned it, and it made no noise. He wondered if the door was locked on the other side. But it wasn’t. It opened silently.

Julian looked through it, expecting to see a room, but there wasn’t one. Instead he found himself on a small gallery that seemed to run all the way round the inside of the tower. The moon shone in through a slit-window, and Julian could just make out that he must be looking down from a gallery into the darkness of a tower-room on the second or third floor of the tower — the third, probably.

He pulled Anne out and the other three followed. There was no sound to be heard. Julian whispered to the others. “We’ve come out on to a gallery, which overlooks one of the rooms inside the tower. It may be a second-floor room, because we know that the ceiling of the first floor has fallen in. Or perhaps it’s even the third floor.”

“Must be the third,” said Dick. “We’re pretty high.” His whisper went all round the gallery and came back to them. He had spoken more loudly than Julian. It made them jump.

“How do we get higher still?” whispered George.