“I must tell Aunt Fanny. She’ll know what to do! Oh I hope the others are safe. What shall we do if the island blows up? I’m glad, glad, glad I told Mr Curton he was a very wicked man.”

And on she ran, panting. Aunt Fanny would know what to do!

Chapter Twenty

Everything boils up

Meanwhile the three boys and Timmy were having a strange journey underground. Timmy led the way without faltering, stopping every now and again for the others to catch up with him.

The tunnel at first had a very low roof and the boys had to walk along in a stooping position, which was very tiring indeed. But after a bit the roof became higher and Julian, flashing his torch round, saw that the walls and floor, instead of being made of soil, were now made of rock. He tried to reckon out where they were.

“We’ve come practically straight towards the cliff,” he said to Dick. “That’s allowing for a few turns and twists. The tunnel has sloped down so steeply the last few hundred yards that I think we must be very far underground indeed.”

It was not until the boys heard the curious booming noise that George had heard in the caves, that they knew they must be under the rocky bed of the sea. They were walking under the sea to Kirrin Island. How strange, how unbelievably astonishing!

“It’s like a peculiarly vivid dream,” said Julian. “I’m not sure I like it very much! All right Tim — we’re coming. Hallo — what’s this?”

They all stopped. Julian flashed his torch ahead and saw a pile of fallen rocks. Timmy had managed to squeeze himself through a hole in them and go through to the other side, but the boys couldn’t.

“This is where the spades come in, Martin!” said Dick, cheerfully. “Take a hand!”

By dint of pushing and shovelling, the boys at last managed to move the pile of fallen rocks enough to make a way past. “Thank goodness for the spades!” said Julian.

They went on, and were soon very glad of the spades again, to move another heap of rock. Timmy barked impatiently when they kept him waiting. He was very anxious to get back to George.

Soon they came to where the tunnel forked into two. But Timmy took the right-hand passage without hesitation, and when that one forked into three, he again chose one without stopping to think for a moment.

“Marvellous, isn’t he?” said Julian. “All done by smell! He’s been this way once, so he knows it again. We should be completely lost under here if we came by ourselves.”

Martin was not enjoying this adventure at all. He said very little, but laboured on after the others. Dick guessed he was worrying about what was going to happen when the adventure was over. Poor Martin. All he wanted to do was to draw — and instead of that he had been dragged into one horrible job after another, and used as a cat’s-paw by his evil guardian.