"Don't talk," hissed Betty, through clenched teeth. "We've got to hold him."

And they did!

A moment later several guards, headed by a man not in uniform, came in sight around the corner of the building and as Will afterward expressed it "the game was all over but the shouting."

For it was Will who headed the relief party and took charge of the capture. And so excited were the girls, that they forgot even to wonder until it was all over.

Adolph Hensler was not easy to handle, even after he found himself looking into the muzzles of two loaded revolvers. Even then he tried to escape and the guard was forced to shoot a couple of bullets over his head before he was scared into submission.

The girls walked home behind captive and captors, too breathless and excited even to think. They had not gone far before they met Amy coming toward them, trembling all over from fatigue and excitement.

"They got him, didn't they?" she asked, linking her arm through Betty's and biting her lip to keep it steady. "I was so afraid they would be too late."

"So were we," said Grace, examining a big black and blue bruise on her arm. "We could have held out just about a minute longer."

"How did you do it, Amy?" cried Mollie. "Did you have to go all the way back to camp to find help?"

"No, I met it coming," she answered.

They stared at her incredulously.

"I was about half way to camp," she explained, "when I saw Will and the three soldiers coming toward me. When I had managed to gasp out what I'd come for they didn't say a word--just put on full speed and ran."

"Mighty lucky for us they did," said Mollie, but Betty interrupted eagerly.

"Doesn't it seem strange to you," she said, "that an armed guard should be coming in this direction just when we needed them? And that Will should be at the head of them?"

"Why, Betty, what do you mean?" Mollie was beginning when Grace interrupted.

"Oh, do you think it can be true?" she cried, seeing Betty's meaning and clinging to it desperately. "Oh, Betty, Betty, if it only is!"

"What are you talking about?" cried Mollie impatiently. "Can what be what?"

"Let's wait," said Betty, quickening her pace, "and let Will tell the story!"

CHAPTER XXV

THE MYSTERY EXPLAINED

After dinner in the living-room of the Hostess House, a snapping, dancing, crackling fire in the grate, and the girls gathered in an expectant semicircle about it.

They were nervous, too, for every once in a while one of them would get up, look out the window, throw an extra log upon the fire and sit down again with a "why-don't-they-come?" look of impatience upon her face.

A ring at the door bell!

"I'll answer it," cried Betty, jumping up and nearly overturning a chair in her eagerness. When she returned a couple of minutes later, her face held a look of unutterable disgust.

"Only one of the guests," she said, as the girls looked up eagerly.

"I was sure that must be the boys."

"They're terribly late," grumbled Mollie, kicking an overturned edge of the rug into place, as if even that small vent to her feelings was a relief. "They'll be all talked out before they get here."

Another ring at the door bell!

This time there was no mistake. A chorus of excited voices greeted Betty as she opened the door for them and a moment later the boys burst into the living-room, fairly exhaling importance. The girls welcomed them eagerly and drew up more chairs before the fire.

"Gee, but we've had some time," cried Allen, fairly panting from exertion and excitement. "If you girls were heroines before, you're more than ever so, now."

"But where's Will?" asked Grace, with that old, anxious look. "I thought he was coming with you."

"He is," Frank answered her. "But he was summoned to a very important conference with the colonel----"

"The colonel!" they cried incredulously, while Grace stamped her foot with impatience.

"What do you mean?" she demanded.

"Just that," he answered, enjoying their mystification too much to enlighten them at once. "When he received the order he told us fellows to come on over and he'd join us as soon as he could break away."

"Oh, Allen, please tell me what it all means." Grace was fairly crying with excitement and eagerness. "Please don't keep me waiting any longer!"

"I'm sorry, Grace--I didn't think," said Allen, in quick compunction.

"It means," he added, with a ring of pride in his voice, "that Will is what we always believed him to be--one of the finest fellows that ever lived. I'm proud to be called his friend!"

"Oh, Allen!" Grace felt blindly for a handkerchief and Betty slipped it into her hand. "Oh, Allen,----"

"But what did he do?" demanded Mollie impatiently. "You haven't gotten to the point yet."

"Well," Allen continued, while Betty put a sympathetic arm about her friend and snuggled close, "all the time we were wondering down in our hearts why Will didn't enlist--although we never doubted he had good reasons," he added hastily, "he was really working harder, spending more time and energy for the government than we ever thought of spending. There's one important thing we forgot--that Will was a secret service man!"

"Oh!" cried Betty, her eyes gleaming in the firelight, "now, I know I guessed right!"

"What did you guess?" asked Allen, remembering to marvel, even in that moment of excitement, how very becoming firelight was to Betty!

"Out with it."

"Why," said Betty, leaning forward eagerly, "after Amy told us that she had met Will and the soldiers half way to the spot where we found the spy, I seemed to see the whole thing as plainly as if some one had told it to me.

"I remembered Will's special interest in the spy the first time we met Adolph Hensler on Pine Island--then how, soon after we saw him here again, Will wrote Grace that he was coming on. That would seem as though he were hot on his trail--"

"He was," said Allen, while the others hung on every word.

"Well, the rest is simple," said Betty. "I suppose that Will kept on shadowing him till he got what he wanted. He was on his way to capture the spy, while we were hanging on to the door, praying for help. Oh, it all fits together like parts of a puzzle!"

"You're a wonder, Betty!" said Allen, while the others drew a deep breath, trying to take it all in. "But there was one little bit, or rather, I should say, big bit, of cleverness on Will's part that neither you nor anybody else could guess at. You remember the code letter we picked up that night on Pine Island?"