“Don’t blow them out,” said Eric, “it would leave a smell—pinch the wicks.”

In a moment the boys were in total darkness, save for the faint glimmer of daylight from the hole in the wall of the cave above their heads. Moving very softly, they crept behind a projecting rock, and squatted down, listening breathlessly.

“‘It’s just like a submarine,’ said Eric, ‘only much too small. But I say,’ he added, bending over the boat, ‘it is a submarine—a tiny one!’”

Soft footsteps were descending the spiral staircase. It must be the spy! What sort of man would he be? Would he carry a revolver? What would he do to the Cubs if he saw them? Perhaps he would throw them into the black water. Or possibly he might force them to go down into the little submarine and take them out to the U-boat, and deport them to Germany. Wild thoughts flew through their minds, and they wished themselves a thousand miles away. Meanwhile, the footsteps were coming quickly along the short passage. The Cubs held their breath, their hearts beating wildly. A yellow beam of light fell on the quay, and in another moment a man stepped up to the water’s edge. The Cubs could see him through a crack in the rocks. As he turned round they saw his face, and Eric caught his breath in a gasp of surprise. It was William Mendel!

Opening the conning tower of the tiny submarine, he stepped down into it. “Shall we shut him in?” whispered Donald, under his breath. Eric shook his head. William Mendel had begun hammering, and making curious noises, inside the boat. It was safe to whisper without being heard. “If Uncle William is the spy,” said Eric, “there’s no need to take him prisoner, and risk getting taken ourselves. If he doesn’t know he’s been discovered, he will go on staying quite happily in the Castle. All we have to do is to get back, tell grandfather the whole story, and have him arrested. All the same I would love to take the old beast prisoner myself! But we shall be serving our country better by having him taken by the police, and made sure of. Think, if he knocked us down and managed to escape!”

The traitor sounded very busy in the boat. He had started the engine. “He’s overhauling his engines,” whispered Eric. “We better take this chance of getting out.” Very softly the two Cubs crept from their hiding place, back along the passage, and up the winding stairs. With a sigh of relief they emerged from the secret room, at last, and closed the sliding panel behind them.

V
JENKINS

“Now, what shall we do?” said Donald.

Eric was deep in thought. “I was going to say—‘Let’s go to grandfather’s study’—but it’s just struck me that Uncle William (ugh! the beastly traitor!) is sure not to be working alone. He must have a fellow spy helping him. I am not sure that we ought not to find out who it is before we speak to grandfather. He’s sure to get the wind up frightfully, and so will the police, and, of course, the fellow spy will just bunk, with all the plans.”