"But n.o.body has tried our door yet," said Carstairs, "and it's a consoling thought."

They lay a long time, and heard the continual thump of feet about the place. It suggested at first the thought of plunder, but when John peeped out he did not see anybody bearing things from the house. He beheld instead a sight that caused him to summon the others. A young man had ridden up, and, as he dismounted, all the officers, several of whom were in the uniform of generals, paid him marked deference.

"It's a prince," whispered Carstairs. "It may be the Crown Prince himself, but I can't say, the light isn't good enough."

"And there are other princes behind him," said Wharton. "See the officers still kotowing. I didn't suspect that we had taken a room in a royal residence."

"I'd give a lot to know what they're about," said Carstairs. "Something big must be afoot."

"They're still moving about the house," said John. "We've got to wait.

That's all."

They went back to their places on the floor, and waited as best they could, but they heard the sounds for a long time. After an interminable period they went back to the window and saw the prince and the cavalry riding away. The cannon too departed. A dozen Uhlans however remained posted on horseback about the house. The noises inside ceased.

"I can't make it out," whispered Carstairs. "Why should they go away and leave those Uhlans there guarding the house?"

"There must be something inside very precious to them," replied John.

"But what is it? Apparently the house itself is abandoned by all save ourselves."

"I don't know the answer, but my watch tells me it's far in the night.

We've had our sleep and rest, and we must try to slip by the Uhlans and get away. Now's the time too."

"Right you are, John," said Wharton, as he felt once more of his precious pocket. "We can't linger, and risk being caught in a trap here."

"But I hear somebody still moving about the chateau," said Carstairs.

"Wait a minute, boys."

He looked through the empty keyhole, and announced that he saw a faint light or the reflection of a light in the hall.

"Something's on foot," he said. "If their officers are sleeping here I should think they'd take the lower rooms, but it seems to me that they're fond of the top of the house, overfond of it."

John who was peeping out at the window once more announced that the Uhlans were still keeping a vigilant watch. They were riding slowly back and forth, and he had no doubt there were others in the rear of the chateau.

"But I repeat we mustn't linger," said Wharton. "Suppose we hold our automatics ready and slip out."

"Suits me," said John, and he cautiously unlocked the door. The three with their hands on their weapons stepped into the hall, where they noticed the faint glimmer of light, of which Carstairs had spoken. They stood there silently for a moment or two, pressing themselves against the wall, where they would be in the shadow.

"I think the light comes from above," said Carstairs. "You'll notice that the little stairway leads upward, apparently to the roof."

Wharton held up his hand, and the three were so still they scarcely breathed.

"Don't you hear it?" whispered Wharton. "That sound from the roof, the sputtering and crackling."

"I do hear it," said John, listening with all ears. "It's a faint sound, almost like the light crackling of fire. What does it mean Wharton?"

"The wireless."

"The wireless?"

"Yes, while we were sleeping the Germans were installing a wireless outfit on the roof, and it's talking. I tell you, boys, it's talking at a great rate, and it's saying something. You mayn't have noticed it, but the chateau stands on a hill, with a clear sweep, and our wireless here is having a big talk with distant stations. We've been sleeping, but the Germans never sleep."

"I suppose you know what you're talking about, Wharton, and you're sure it's a wireless outfit," said John.

"It's impossible for me to be wrong. I could never mistake the sound of the wireless for anything else."

"And it's there on the roof of this chateau, which belongs to us by right of occupancy, chattering away to German forces elsewhere!" said Carstairs in an indignant whisper.

"It's doing a lot more than chattering," said Wharton. "They wouldn't install a wireless on the roof of a house at this time of the night, merely for a little idle summer conversation. You saw that a prince and generals came here, and undoubtedly they ordered it done."

"Whatever they're talking about," said Carstairs, "it's not likely they're talking about us, so now is our chance to slip away."

"I'm not going to leave the chateau just now," said Wharton.

"Then what are you going to do?"

"I'd like to see the wireless on the roof and the man who is working it."

John glanced at Wharton. The light was very dim, but he noticed a spark in Wharton's eye, and he knew that something unusual was working in the back of his head.

"I think I'd like to have a look at the roof myself," he whispered.

"If you chaps are bent on going up there," said Carstairs, "I'm bound to go with you. But we'd better keep our automatics in our hands."

They emerged from the shadow of the wall, and reached the foot of the stairway that led to the roof. The door at the top was open, as the moonlight was shining down, and Wharton boldly led the way, walking on tiptoe, his automatic in his hand. At the open door John and Carstairs crowded up by his side, and three pairs of eyes peeped out at once.

They saw two men on the roof both with their backs turned to them. One was the operator of the wireless, sitting on a camp stool, working the instrument. The other, in an officer's uniform, was dictating messages.

John surmised that they were talking with a station to the eastward, where some lofty ranges of hills ran.

But Wharton was the most deeply stirred of the three. The spark in his eye was enlarging and glowing more brilliant, and a great resolve had formed in his mind.

"There's nothing that we can do here," said Carstairs. "We'd better go at once."

"We're not going," said Wharton in a fierce whisper. "I can use the wireless, and that's just the instrument on which I wish to exercise my skill. I've heard enough to know they're not talking in code."

"Wharton, you are mad!" said John.

"If so, I'm mad in a good cause. Inside of ten minutes some German general will be hearing remarkable news from this station."

"I tell you again you're mad."

"And I tell you again I'm not. I'm a crack wireless operator and this is my chance to prove it. I'm going up there. All who are afraid can turn back."

"You know that if you're resolved to go mad we'll go mad with you. What do you want us to do?"

"John, club your automatic, and hit that officer on the back of the head with it. Hit hard. Don't kill him, but you must knock him unconscious at the first blow. Carstairs and I will choke all but a spark of life out of the operator."

The three emerged from the stairway upon the flat portion of the roof where the wireless plant had been installed not more than four or five feet away. They made not the slightest sound as they stole forward, but even had they made it the two Germans were so deeply absorbed in their talk through the air that they would not have heard it.