“I thought we’d find it,” said Carter exultantly.  “It’s an ideal location, up here in the mountains.  I’d better smash it at once.”

“Wait,” warned Jane, thoughtfully, “they spoke of having received a wireless message from those dreadful X-boats lying there off the coast.  If we could only find their code-book, perhaps—­”

“Right,” cried Carter, catching her idea at once.

Together they descended to the room below and began ransacking the desk, Jane holding the light while Carter examined the papers they found.

“Their system sometimes is bad for them,” said Carter.  “Here’s a ledger with the names of all the men employed here and the amounts paid to each.  And look,” he went on excitedly, “look what the stupid fools have done with their German methodicalness—­here are entries showing all the supplies they obtained, from whom they got them and what they cost.  There’s evidence here for a hundred convictions.  We’ll just take that book along.”

There was one small drawer in the desk that was locked.  Ruthlessly Carter smashed the woodwork and pried it open.  Its only contents was a small parcel, a folded paper in a parchment envelope.  Hastily he drew forth the paper and studied it intently.

“It’s a code,” he cried, “a naval code, evidently the very one they used to communicate with those boats.  I’ll wager the Washington people even haven’t a copy of it.  That’s a great find.  Come on, we’ve got enough for one night.”

“Do any of the men in our party understand wireless?” asked Jane as they descended.

“Sure,” said Carter, “Sills does.  He used to be the radio man on a battleship.”

“Couldn’t he be left on watch here?” suggested Jane, “and try to signal those X-boats and keep them waiting until to-morrow night?  Maybe by that time our—­”

“I get you,” cried Carter; “that’s a good idea.  Explain it to the Chief.”

As Jane unfolded her plan, suggesting the possibility of sending American cruisers out to search for the X-boats after Sills had lured them by false messages to the surface, Fleck heartily approved of it.

“I’ll leave Sills here with one other man to guard the house,” he said.  “We’ll have to let poor Dean’s body remain here for the present, too.  We’ll need all the room in the cars for the prisoners.”

There was still much to be done.  While some of the men were unceremoniously carrying out the shackled prisoners and piling them in the cars, others, under Carter’s direction, crippled the three “wonder-workers” and dismantled them, carrying their dangerous cargo of bombs into the woods and concealing them.