“Would it not be better first to warn the inmates of the chateau of what is afoot?” asked Alan.

“No, that wouldn’t do at all, because neither we nor the Emperor know which of the attendants are faithful and which are treacherous. We’ll have to play this game single-handed, boys.”

So finally it was agreed to adopt the scheme as originally suggested by Bob. Their preparations for departure at that hour of the night were noted with great curiosity by the other aviators from the Austrian hangars, and Capt. von Schleinitz, the young officer who had driven to the hospital with them and told them about local conditions when they first arrived, said casually:

“You choose a peculiar hour for starting off again, gentlemen.”

“Yes,” Bob answered him, “we are only going on a small flight. Mr. Napier is not returned yet, so we will, of course, be back for him.”

“How I wish that I might be privileged to accompany you on one of your flights!”

Alan and Buck overheard his remark, and after excusing themselves for the seeming discourtesy, took Bob aside.

“Listen, Bob,” Alan whispered. “Why not take Captain von Schleinitz along with us on to-night’s expedition. He impresses me as a brave, good fellow, and the presence of a regular Austrian army officer aboard might prove of great help in several ways. Patrolling military aeroplanes might stop us with all sorts of questions once we get into the air.”

“I guess you’re right, Alan,” said Bob thoughtfully. “Let’s take him into our confidence then and explain the whole matter.”

This was accordingly done. The Austrian was horrified by the revelation of the plot and urged all possible haste. By ten-thirty the Flyer’s engines were started and the short flight to Schoenbrunn was begun. No lights were shown aboard as the boys were anxious to avoid all unwelcome attentions.