But he had been prepared, and was flying away.

Down below there was now a great glare from the burning wreckage, lighting up the whole scene.  And suddenly there was a sharp breaking out of rifle fire.  At first he thought the men below had seen them, and were firing upward.  But in a moment he saw the truth.  Bray Park had been attacked from outside!

Even before they reached the ground, in the meadow where Harry and Jack had emerged from the tunnel, and Harry and Dick saw, to their wonder and delight, that the ground swarmed with khaki-clad soldiers.  In the same moment Jack ran up to them.

“The soldiers have the place surrounded!” he cried, exultingly.  “They must have believed your letter after all, Harry!  Come on — there’s a boat here!  Aren’t you coming over?”

They were rowing for the other shore before the words were well spoken.  And, once over, they were seized at once by two soldiers.

“More of them,” said one of the soldiers.  “Where’s the colonel?”

Without trying to explain, they let themselves be taken to where Colonel Throckmorton stood near the burning wreckage.  At the sight of Harry his face lighted up.

“What do you know about this?” he asked, sternly, pointing to the wrecked airship.

Harry explained in a few words.

“Very good,” said the colonel.  “You are under arrest — you broke arrest this morning.  I suppose you know that is a serious offense, whether your original arrest was justified or not?”

“I felt I had to do it, sir,” said Harry.  He had caught the glint of a smile in the colonel’s eyes.

“Explain yourself, sir,” said the colonel.  “Report fully as to your movements today.  Perhaps I shall recommend you for a metal instead of court marshalling you, after all.”

And so the story came out, and Harry learned that the colonel had never believed Graves, but had chosen to let him think he did.

“The boy Graves is a German, and older than he seems,” said the colonel.  “He was here as a spy.  He is in custody now, and you have broken up a dangerous raid and a still more dangerous system of espionage.  If you hadn’t come along with your aeroplane, we would never have stopped the raid.  I had ordered aviators to be here, but it is plain that something has gone wrong.  You have done more than well.  I shall see to it that your services are properly recognized.  And now be off with you, and get some sleep.  You may report to me the day after tomorrow!”

THE END