“I’ll wait another ten minutes and then I’m going,” Julian decided. “I’ve had about enough of hiding in a dark, dirty tunnel waiting for a train that doesn’t come! Maybe it has decided to stay in Olly’s Yard for the night.”

After ten minutes he gave it up. He left the tunnel, went into Kilty’s Yard and then up the path to the moors. He hurried along it, eager to see if Dick was at the other end of the tunnel. Surely he would wait there till Julian came back!

Dick was there, tired and impatient. When he saw a quick flash from Julian’s torch he answered it with his own. The two boys joined company thankfully.

“You have been ages!” said Dick, reproachfully. “What happened? The spook-train went back into the tunnel ages and ages ago. It only stayed about twenty minutes in the yard again.”

“Went back into the tunnel!” exclaimed Julian. “Gosh, did it really? Well, it never came out the other side! I waited for ages. I never even heard it — though I did hear a very faint rumble once, or thought I did.”

The boys fell silent, puzzled and mystified. What sort of a train was this that puffed out of a tunnel at dead of night, and went back again, but didn’t appear out of the other end?

“I suppose the entrance to that second tunnel the porter told us about is really bricked up?” said Julian at last. “If it wasn’t, the train could go down there, of course.”

“Yes. That’s the only solution, if the train’s a real one and not a spook one,” agreed Dick. “Well, we can’t go exploring the tunnels now — let’s wait and do it in the day-time. I’ve had enough to-night!”

Julian had had enough too. In silence the two boys went back to the camp. They quite forgot the string in front of their tent, and scrambled right through it. They got into the sleeping-bags thankfully.

The string, fastened to George’s big toe through a hole she had cut in her sleeping-bag, pulled hard, and George woke up with a jump. Timmy was awake, having heard the boys come back. He licked George when she sat up.

George had not undressed properly. She slipped quickly out of her bag and crawled out of her tent. Now she would catch the two boys going off secretly and follow them!

But there was no sign or sound of them anywhere around. She crawled silently to their tent. Both boys had fallen asleep immediately, tired out with their midnight trip. Julian snored a little, and Dick breathed so deeply that George could quite well hear him as she crouched outside, listening. She was very puzzled. Someone had pulled at her toe — so somebody must have scrambled through that string. After listening for a few minutes, she gave it up and went back to her tent.

In the morning, George was furious! Julian and Dick related their night’s adventure, and George could hardly believe that once again they had gone without her — and that they had managed to get away without disturbing the string! Dick saw George’s face and couldn’t help laughing.