“What for?” said Dick. “I can’t make head or tail of this!”

George swung her torch on the three boys and then asked a sudden question: “I say — where’s Anne?”

“Anne! She didn’t want to come back with us through the tunnel, so she ran over the moorlands to meet us at the other end, by Olly’s Yard,” said Julian. “Gosh, she’ll be worried stiff, won’t she, when we don’t turn up. I only hope she doesn’t come wandering up the tunnel to meet us — she’ll run into those men if she does.”

Everyone felt worried. Anne hated the tunnel and she would be very frightened if people pounced on her in the darkness. Julian turned to George.

“Swing your torch round and let’s see these caves. There doesn’t seem to be anyone here now. We could have a snoop round.”

George swung her torch round, and Julian saw vast and apparently fathomless caves stretching out on either side, cut out of the sides of the tunnel. Jock saw something else. By the light of the torch he caught sight of a switch on the wall. Perhaps it opened the hole in the wall.

He crossed to it and pulled it down. Immediately the place was flooded with a bright light. It was a light-switch he had found. They all blinked in the sudden glare.

“That’s better,” said Julian, pleased. “Good for you, Jock! Now we can see what we’re doing.”

He looked at the spook-train standing silently near them on its rails. It certainly looked very old and forgotten — as if it belonged to the last century, not to this.

“It’s quite a museum piece,” said Julian, with interest. “So that’s what we heard puffing in and out of the tunnel at night — old Spooky!”

“I hid in that truck there,” said George, pointing, and she told them her own adventure. The boys could hardly believe she had actually puffed into this secret place, hidden on the spook-train itself!

“Come on — now let’s look at these caves,” said Dick. They went over to the nearest one. It was packed with crates and boxes of all kinds. Julian pulled one open and whistled.

“All black market stuff, I imagine. Look here — crates of tea — crates of whisky and brandy — boxes and boxes of stuff — goodness knows what! This is a real black market hiding-place!”

The boys explored a little further. The caves were piled high with valuable stuff, worth thousands of pounds.

“All stolen, I suppose,” said Dick. “But what do they do with it? I mean — how do they dispose of it? They bring it here in the train, of course, and hide it — but they must have some way of getting rid of it.”

“Would they repack it on the train and run it back to the yard when they had enough lorries to take it away?” said Julian.