"We 're right under the corner Guild House," he whispered. "The bunch of wires comes down here. Here they are, Egmont. You can see them!"

Egmont stepped eagerly forward and gazed at the strands of electric wires that ran through a metal tube over his head, and then spread out in all directions. They had

been installed by an expert, for they were carefully protected and firmly fastened to little brackets in the sides of the walls.

"Now we 'll teach the Huns a trick or two!" murmured Bob, in a low voice. "Let me have your cutters, Guy. I'll begin on this wire."

CHAPTER IV

UNDER THE GUILD
HOUSE

THE plan of the young Vigilantes was simple, and they worked silently and swiftly. Bob clipped the wires where they were exposed after leaving the metal tube, cutting a piece from each one and then replacing it with a strip of the fake wire, skilfully concealing the joinings with extra strips of insulation. They worked

these over carefully, so

that no inspector, sent

House over our heads," replied Guy. "They 're carousing, as usual."

The muffled rumbling overhead could hardly be identified as laughter and singing; but Bob assured his cousin that Guy was right. They had heard it before, when

Finally Bob dropped his arms with a grunt of satisfaction. "There! I don't "There! I don't believe any one will discover the trick," he said. "What do you think?"

"Listen!" exclaimed Egmont; "what 's that noise?" holding up a hand.

"This metal tube runs directly into the cellar of the Guild House," he explain ed, "and if the cellar door is open, the noise comes right through it. There, they 've closed the door, and we can't hear them any more."

The muffled rumble of voices had

subterranean hiding-place. They waited a few moments to see if it was renewed.

"How'd they get down here to string the wires?" Egmont whispered, after a long pause.

"Followed the sewer as we did, I suppose," replied Bob. "They must have. known about it. They had maps and plans of the city long before the war. Brussels was full of German spies. They knew more about the city than lots of Belgians. I should n't be surprised if they had the plan for mining it drawn up years ago."

"Yes, there were traitors-" Guy began, when Bob interrupted him with a cautious whisper:

"The cellar door 's open again. Hear the noise!"

"We don't want to do that," was the murmured reply, "but I 'm crazy to get a look at what 's above."

Bob stopped a moment and considered. "Guy," he said then, "stand by the metal pipe and listen. I 'm going through this door. You can give me the signal if any one opens the cellar door above, and I can get back without being seen."

Egmont was n't quite sure that they should undertake so risky an enterprise, but Guy nodded his head and took his station where the wires came through the roof. Bob once more applied an upward pressure to the iron door, and, with his cousin's assistance, it was soon forced open. They listened intently for some time before making another move. There was no

"I'd like to get a peep into the Guild House to see what they 're doing," remarked Guy. "We might learn something important."

"Perhaps there's a way of getting down here from the cellar," suggested Bob; "I 'm going to look for it."

Guy and Egmont were both eager to join in the search, and they began a careful examination of the sewer wall.

Suddenly Bob touched something hard and smooth that was neither stone nor brick.

"What's this?" he asked excitedly. Then, a moment later, he answered his own question. "It 's an iron door! Yes, here are the hinges. It's curved to fit the roof of the sewer. It must be the entrance to the cellar!"

Their excitement was great, but for a moment they were undecided what to do. If the door led directly into the cellar of the Guild House which the Germans were using as an officers' club and meeting-place, it might be dangerous to force it open.

Finally, however, Bob placed both hands against the iron plate and pushed upward. The door yielded slowly to his effort. "It 's not locked!" he whispered. "See! I can open it."

musty cellar as in the sewer.

"Hand me the candle," Bob whispered. "I can't see a thing up here."

Then, holding the candle, he mounted on his cousin's shoulders until he was high enough to thrust his head and shoulders through the opening. From this point of vantage, he got a view of the space above.

"It is n't the cellar," he whispered down to the others. "It's a sort of subcellar. There's another above this. I don't believe any one comes down here very often." "It may be the wine-cellar," replied Eg

mont.

"Then we 'll have to be careful, for they 're drinking enough up there to need a new supply before long, Anyway, I 'm going to explore."

Placing the candle on the floor, he pulled himself up until he stood in the black, musty subcellar of the old Guild House. The place was filled with boxes and barrels, many of them filled with rare old vintages of the best wine, and others, broken open and empty, testifying to the thirst of the invading enemy. Guy and Egmont waited anxiously below.

But it was n't casks of wine that Bob Lane was looking for. Now that he was in the subcellar, he was curious to know how it was entered from above. He finally

but he was still cautious. Returning to the iron door, he whispered to his companions: "I've found the stairs leading above. I'm going up to explore."

"Better not, Bob," expostulated Guy. "You might get caught, and then all our fixing of the wires will be wasted."

"I'm not going to get caught, nor am I going to spoil our job," was the reply. "I want you and Egmont to close the door, and keep it closed until I rap on it. No, I can open it from this side when I want to return."

"Bob, you'll be captured and shot!" exclaimed Egmont. "Please don't do it!"

"I'm not going to run any risk, Egmont. If anybody comes down here, I can hide behind the boxes and casks. There 's plenty of room. He could n't find me in

Creeping slowly up the stairs, Bob fumbled around in the dark for the latch of the door above. He had extinguished his candle and dropped it in his pocket for future use. A light might betray him.

It was an ordinary trap-door that he encountered, let into the floor of the cellar proper, and swinging upward. Bob tested it and found it unlocked. Inch by inch, listening cautiously, and peering intently through the widening crack, he raised it until it was far enough open to give him a good view of the upper cellar.

Like the subcellar it seemed filled with a motley collection of boxes and casks. They rose tier upon tier on all four sides. It was not necessary to use his candle to see. A path of strong daylight poured through an open doorway at the head of

the stairs that led into the rooms above. It was through this opening that the boisterous laughing and carousing came.

Bob paused a long time, listening and looking, holding the trap-door in such a position that he could quickly close it if any one appeared. The cellar, like the subcellar, was deserted, but there was more danger of being surprised here. He had no desire to push his investigations further.

He had learned all that was necessary. The old German coffee-merchant, who had lived in the corner Guild House before the invasion, had secretly prepared his place for the reception of the German officers. The subcellar had been dug below the main cellar after the innocent appearing coffee-merchant had taken possession of the building, and the opening into the abandoned sewer had then been cut and the iron door fitted to it.

Perhaps the mines to blow up the square had even been laid prior to the invasion, in order to destroy that part of the city in the rear of the Belgian army if, for any reason, the Germans had been checked. It was certainly no worse than many other of the diabolical plans laid by the Huns.

The boisterous carousing of the German officers struck Bob with peculiar force, and made him shudder with disgust and rage. While the Belgians suffered the torments of hunger and fear, the invaders drank toasts, and plotted, and planned further outrages. The blood mounted to his forehead, and his heart swelled with anger.

"I'd like to blow up the whole square and kill them all!" he muttered under his breath. "I could do it, too."

He thought of the great power that had suddenly been put in his possession. He had not examined the upper ends of the wires coming through the iron tube, but he had no doubt they were connected with an electric battery, or could be connected in a short time. By replacing the pieces of wire he had cut out, he could then exterminate all the staff officers assembled in the building. More than that, he could blow into eternity the German regiments quartered in the different buildings of the square.

But he would wreck the most magnificent buildings of any capital in the world -the superb Grande Place, second to none in Europe, with the beautiful Hôtel de Ville, the galleried and much-gilded Maison du Roi, and the many guild houses of the archers and skippers, the printers and merchants. Not only that, but hundreds of innocent Belgians-men, women, and children-would meet their fate with the Germans.

No! such a thought was too terrible for consideration. He had to be content with his present work. He had to save rather than destroy. It was not the mission of the Boy Vigilantes to make conditions worse in Brussels, even though a few important German officers would be killed in the process.

When Bob rejoined his two companions in the sewer, they listened eagerly to the brief account of his discoveries in the cellar above. The chief importance of his investigation was that it confirmed the suspicions of the boys: that the old German coffee-merchant had been a spy who had prepared the way for blowing up some of the finest buildings of Brussels if the city resisted invasion.

"And now," Bob added, "they intend to blow it up if they 're forced to evacuate." "Well, they'll be disappointed," replied Guy, grinning.

It was getting late, and Egmont was anxious to return. Their discovery of the perfidy of the invaders had increased his bitterness toward the Germans, and he led the way out of the sewer in silence.

It was dark when they finally crawled along the canal and scrambled to the street above. They stood there a moment, a little dazed by their surroundings. Bob was the first to recover his wits.

"We ought not to have come up together," he whispered. "We'd better scatter now."

The words were scarcely out of his mouth when shadowy figures seemed to spring up all around them. They started to separate-and ran plump into the arms of German soldiers!

I-THE BLACK

"WHAT ails you, Leonard? You appear like the 'Wreck of the Hesperus,' or words to that effect." Frank Taylor looked up from the kit he was overhauling with curiosity in glance and voice.

"Nothing," growled his tent-mate, shortly.

"Don't look like nothing when a goodnatured chap like you turns gloomy. Sick of your bargain with Uncle Sam?"

The tanned face reddened darkly. "Nobody but you would dare say that to me, Taylor, and you'd better not." Leonard's square shoulders straightened, then drooped again as their owner sunk his chin in his open palm and fell silent once more.

"Come on, 'fess up your 'ghastly secret' and get it out of your system," teased Frank, in in nowise disconcerted. "It does n't do any good to get grouchy."

"That's easy talk for you-you have n't had to smash somebody's cherished plans and expectations-deal 'em all a death-blow at one fell swoop. It 's enough to make a grouch out of Job." "You don't say! I suppose I am not to ask for details?"

Leonard Preston arose and began pacing the bit of floor space between the two cots. "Oh, it 's no secret, Frank. It's just that it's hard to talk about it. Of course, it's Amy-my sister, you know. Poor little soul, I 'm all she 's got, and she depends on me to see her through the hard places. I'd rather face a firingsquad than tell her we 're ordered to France without so much as a chance to say good-by."

"Great Scott, man, be glad of it! What comfort is there in a moist farewell? Excuse me from such," said Frank, fervently.

"You don't seem to remember that I 've been here a year, doing instructing since I finished my own training, and I was to have four weeks, beginning now."

"Leonard, you surely don't grieve after a holiday when-"

The tall pedestrian interrupted with a scornful gesture. "Do you suppose it 's because I want it? Don't you know I'm aching in every nerve I own to get across and do something? But Amy 's lonesome as the dickens, and she 's planned every hour of my twenty-eight days and how to use it. Even engaged a little bungalow on Spring River to spend it in, and paid for it out of her school-teacher earnings. She has n't any money to throw to the birds, either, since she got through with her oculist and buying the glasses he ordered. What do you suppose she called it?" "It? The oculist? Why doctor, probably-they usually do, you know." "Oh, get out! The bungalow."

'Rest Cottage' or 'Honeysuckle Lodge.' Girls will be girls."

"That's where you show your ignorance of this particular girl. 'Cyclone Cliff,' if you please-anything sissy about that?"

Frank stared with mock incredulity. "Well, I take off my hat to any feminine brain that evolved that title!" he declared. "Too bad it 's knocked in the head."

"Yes. Amy will be all broke up-Jove, I dread to get her next letter, Frank!"

"I don't blame you, old man; but it 's one of the ordeals of war and can't be helped. Get busy and forget it."

"Easier said than done. Poor kid! nobody but me, and I 've got to hurt her so! If only she had n't set her hopes so hard on her little Cyclone Cliff!"