"Been considerable going in and coming out of vehicles, generally automobiles," he announced.
"And private cars are almost taboo in all Germany these dark days, they tell us," mentioned Jack sagely. "That makes it look as if some sort of military business might be transacted in this isolated place. Gee! I tell you it's getting my curiosity whetted to a fine point, all this mystery. But we're going in, of course, Tom?"
"Some way or other, Jack. If the entrance is closed and locked we can climb over the fence, all right. But no need of worrying about that, because I already see the gates are ajar. Come on."
So they slipped into the enclosed grounds, actuated by an impulse, wholly unconscious of what might be awaiting them. They had been drawn into the adventure simply on account of a praiseworthy desire to be of service to some unknown one who seemed to be in trouble. And neither of the boys even vaguely suspected as yet what strange happenings would confront them before many minutes passed by.
CHAPTER XIX
A NEST OF SPIES
Neither of the air service boys had any doubts now with regard to the character of the grounds they were invading at dead of night. It must be a private estate. Once it may have been kept up through a lavish expenditure of money, but of late years things had evidently been allowed to grow more or less wild.
Tom was following what appeared to be the drive. It was not difficult to do so, because of the moonlight that sifted down through the bare branches of the neighboring ornamental trees, now destitute of foliage.
The house was presently discovered. Just as Tom anticipated, it was a rather large building, that might even be called a mansion, or château. It lay half buried amidst a prodigious growth of trees and bushes.
Jack fancied there was a sort of haunted air about the place, something uncanny, as he told himself. And then those sobs or screams could not be forgotten.