But just as she was about to try and get out, the engine gave a loud “choo-choo,” and began to move backwards! It ran down the lines a little way, then forward again, and this time its wheels were on the set of lines that led to the second tunnel, where the small opening now showed so clearly in the wall.

George didn’t dare to get out of the moving train. So there she crouched as the engine steamed quickly to the hole in the wall that stretched right across the other tunnel. That hole just fitted it! It must have been made for it, thought George, as the train moved through it.

The train went right through and came out in another tunnel. Here there was a bright light, too. George peered out through the crack. There was more than a tunnel here! What looked like vast caves stretched away each side of the tunnel, and men lounged about in them. Who on earth were they, and what were they doing with that old train?

There was a curious noise at the back of the train. The hole in the stout brick wall closed up once more! Now there was no way in or out. “It’s like the Open Sesame trick in Ali Baba and the Forty Thieves,” thought George. “And, like Ali Baba, I’m in the cave — and don’t know the way to get myself out! Thank goodness Timmy is with me!”

The train was now at a standstill. Behind it was the thick wall — and then George saw that in front of it was a thick wall, too! This tunnel must be bricked up in two places — and in between was this extraordinary cavern, or whatever it was. George puzzled her head over the strange place, but couldn’t make head or tail of it.

“Well! Whatever would the others say if they knew you and I were actually in the spook-train itself, tucked away in its hiding-place where nobody in the world can find it?” whispered George to Timmy. “What are we to do, Timmy?”

Timmy wagged his tail cautiously. He didn’t understand all this. He wanted to lie low for a bit and see how things turned out.

“We’ll wait till the men have gone away, Timmy,” whispered George. “That is, if they ever do! Then we’ll get out and see if we can manage that open-sesame entrance and get away. We’d better tell Mr. Luffy about all this. There’s something very queer and very mysterious here — and we’ve fallen headlong into it!”

Chapter Sixteen

In the tunnel again

Jock was really enjoying himself at the camp. He had a picnic lunch with the others, and ate as much as they did, looking very happy. Mr. Luffy joined them, and Jock beamed at him, feeling that he was a real friend.

“Where’s George?” asked Mr. Luffy.

“Gone off by herself,” said Julian.

“Have you quarrelled, by any chance?” said Mr. Luffy.

“A bit,” said Julian. “We have to let George get over it by herself, Mr. Luffy. She’s like that.”