"That's just what I plan on doing! You see, it's like this," explained Ned. "As we came up here I noticed that this rambling old building seems to have been built at different periods. Part is in good repair, but part has almost fallen down. The Germans in shelling the place added to the dilapidated condition of the older section. On the north side a large portion of the older structure is in ruins."
"I see," interrupted Jimmie. "And when this secret door opened up, you figured that we could go down into the basement and find a passageway leading to the ruined old part that has been knocked to pieces. Then if there's a hole between the two we may be able to crawl out into daylight and be on our way before these fellows get wise to the game."
"Exactly," agreed Ned. "Now let's go carefully and keep quiet. There's no knowing whether we shall get out or not, but there's no need of disturbing these fellows in either case. Get your searchlights ready."
"But, Ned," protested Jack, "didn't this officer say he'd do all he could for us? Don't you think he'll keep his word?"
"It is not his disposition I question," Ned replied, "so much as his ability. I don't know how much influence he has."
"Guess you're right," put in Jimmie. "Let's be on our way, and get back to the little old Grey Eagle. This bed's fine, but I'd prefer sleeping on the ground under our own airship to being here."
Carefully throwing the rays of their searchlights on the floor of the passageway the boys silently stepped through the small door which had been found by such a peculiar accident.
After entering the passage Ned turned to examine the mechanism that operated the section of wall, and without any difficulty discovered what he sought. After a moment's careful scrutiny the lad touched a part of the apparatus and was highly pleased to notice the door swing back into place. Not a sound except the slight humming of the motor accompanied the operation. The device worked perfectly.
"Now, how can we get out again in case we have to come back?" questioned Harry uneasily. "You've got us in here for keeps!"
"That's easy," declared Ned confidently. "All that is necessary is to touch the lever completing the circuit and the motor operates. It doesn't make any difference whether the circuit is completed from the room or from this passageway. The motor operates when the circuit is closed."