and paled. And Fen knew then that he would not be able to run down the mountain as he had run up-that he would not even be able to walk down-alone-so far, so far, to the world. He caught desperately at Siddereticus's robe; but it melted out of his hand, and he was left in utter darkness alone.

There was a sort of crash, and, bewildered, he found Sally's arms around him. She was holding him rather tight, and her face was quite red.

"Fen! What is it! What is the matter!" she was gasping. The beads she had been stringing were rolling about the deck.

"I don't know," said Fen; "nothing. What did I do? You look awfully queer."

"You looked awfully queer!" said Sally. "Goodness, you frightened me, Fen! You'd been asleep for ever so long, when all of a sudden you cried out, 'Oh, if you leave me here-alone-I-shall die!' and you nearly stood right up. I thought you were going to."

"I'm sorry I frightened you," said Fen. "I was dreaming, I think. Sally! Your eyes are all wet!"

"They 're not!" replied Sally, hotly. "Here, lean back, now; is that pillow right? Gracious! Look at all my beads -all over the deck!"

But Fen was looking out to sea. Farremoved and tranquil lay the blue hills of the coast unchanged, unchanging. Only the cobweb veil of distance lay between Fen and those mountain-sides where the gleaming flowers were now closed, each holding in its heart an opalescent drop of starlight.

He looked away again. Sally was gathering the scattered beads, and her cheeks were still flushed.

"I'm awfully sorry I bothered you so, Sally," said Fen. "I wish I could help you pick them up."

And, to his infinite surprise, Sally jumped to her feet and kissed his cheek suddenly.

CHAPTER V

UNDER LOCK AND KEY

"HALT!" a sharp voice commanded.

There was no need to give this order, for the boys were already prisoners in the cordon of soldiers that had surrounded them. A smart lieutenant came up and peered at them.

"Ach! Boys!" he sniffed in disgust; then, grinning, he added, "but big boys all over fifteen!"

Bob faced him defiantly, and said: "No, thirteen."

"That is for the commandant to say," was the sneering reply. "I shall put you down as fourteen. What is your name?"

He whipped out a note book, and under the nearest lamp began writing a description of Bob.

"Your name?" he snapped out again, when the boy hesitated. Torn between a desire to give a fictitious name and an inclination to escape by running away while the officer was off his guard, Bob hesitated another second. Then, realizing the futility of trying to conceal his identity, he replied boldly:

"Robert Lane!"

"Lane! Lane! Is it a German name? Was one of your parents German?"

"No!" exclaimed Bob, sullenly. "There 's no German blood in me. My mother was a Belgian, and my father an American."

"American!" The word came out viciously. "American!" he repeated, growing very red in the face. "They 're worse than the French or English. They are Yankee pigs. They think they can fight, but they're bluffers-money-makers-little traders!"

"They can fight, you 'll find," interrupted Bob. "They 'll give the German troops a run for their money."

"Ach! Fight!" scornfully. "They 'll run the first time they hear our guns." "How about Château-Thierry!" Bob in

terrupted boldly. "Did n't they fight and lick the Germans there?"

"Eh! What's that? Château-Thierry?" "And Belleau Woods!" continued Bob, defiantly, his anger up. "Did n't they drive your best troops out there?"

The surprise and anger of the officer threatened to bring on an attack of apoplexy. His veins swelled up and his face grew nearly purple with rage. But his prisoner was a boy, and he would treat him disdainfully.

"I know nothing about the places you speak of," he replied loftily, shrugging his shoulders. "There are no such places; and if the Yankee pigs are there, it must be far behind the lines, where German bullets can't reach them."

Bob laughed good-naturedly, for now that he had betrayed so much of the knowledge that had filtered in to him through his Vigilantes, he was boastful enough to want to go farther.

"Château-Thierry is right in the thickest part of the fighting," he replied, "and the Germans had to get out of it in a hurry when the Americans attacked them. Thousands of them were killed and wounded or captured."

"Americans, you mean!"

"No, Germans, and some of your best troops."

In his enthusiasm Bob had forgotten that he was talking to a German officer, and his knowledge of such intimate progress on the West Front suddenly aroused the other's suspicion. He leaned forward and glared at Bob. Then, with a heavy hand on his collar, he jerked him forward.

"A spy!" he hissed. "A young American spy! Ach! The brave American can repeat this to the commandant, and

then-"

He waved his hands over his head, imitated the action of a firing-squad, and ended with the one word, "Pouff!"

Holding Bob by the collar, he turned to Egmont and Guy: "I shall not want you

to-night. The American spy is the one I was after. Go!"

Guy and Egmont remained stock-still, for it was not their nature to run when one of their companions was in trouble. Seeing their hesitation, the officer grumbled a word of command to the guard, who raised his bayonet and made as if to prod them with it. The boys stepped back a few paces, but did not run.

"Go on home, Egmont and Guy," Bob said. "I'm in no danger. It's all bluff." "We don't want to leave you, Bob," replied Egmont.

"You can't do any good by staying. You'll only get yourself into trouble. I don't mind spending a night in the guardhouse. In the morning they'll release me."

Guy and Egmont reluctantly drew away, and finally disappeared in the shadows of a side street. Bob was led off by his captors and placed under lock and key for the night.

Events had followed one another so fast that his mind was too excited for sleep. He reviewed the day's work in the abandoned sewer, and exulted at the thought that the wires connected with the underground mines had been cut. If the Huns were ever forced to evacuate Brussels, they would attempt to blow up the square with the mines planted under the houses, but what would be their surprise when they refused to go off? Bob smiled to himself as he pictured their consternation.

Toward morning he finally fell asleep, and did not awaken until some time past daybreak. He was finally aroused by a guard, and, after a breakfast of the coarse prison fare, he was ordered to follow him. Curious and a little anxious as to his fate, he accompanied the guard through a long, dark corridor, and came out into a small room where an officer, with many decorations pinned to his breast, was awaiting him. The moment Bob appeared, the young Prussian who had arrested him. came in by another door.

"Is this the American spy you arrested, Lieutenant?" the superior officer asked, turning to the ot

"Yes, he is the Yankee pig. He boasted of his knowledge, and-"

"He's nothing but a youth—a mere boy," murmured the elderly officer.

"He 's old enough to work, and therefore old enough to be a dangerous enemy." "All right. We 'll see what he knows.'

Bob knew he was in for a quiz such as he had never been subjected to before. He recalled what he had heard of the third degree that the police used to give to prisoners back home. Would they resort to physical force, or depend chiefly on browbeating and threats?

The examination began in a leisurely way, and without any show of force or threats. Indeed, the superior officer assumed the attitude of one interested in him, smiling in a benevolent manner occasionally; but he took Bob's whole pedigree, an aide writing down the questions and answers with scrupulous care. When this preliminary had been finished, the officer turned to him and said:

"Now tell me what you said to Lieutenant Bohn last night."

Bob related all he could recall, repeating the conversation word for word. The officer made no comment until he was through. Then, twiddling stubby thumbs over his chest, he added:

"Now tell me how you knew all this. But be careful that you don't tell me a lie. I want nothing but the truth."

"Why, sir," Bob replied truthfully, and with an innocent expression in his blue eyes, "it's common talk. Everybody knows it in Brussels." "Everybody!"

"Nearly everybody-even the boys and girls."

The man scowled and twisted one end of his mustache into his mouth and began chewing it. He was both annoyed and

troubled. troubled. Bob, fearing to be pressed too closely, suddenly thought of a way to divert suspicion from himself.

"Why, even 'La Libre Belgique' says so," he added.

The effect of these words was instantaneous. The fatherly, benevolent expression on the officer's face disappeared, and

a look of rage succeeded it. He became

red, and then purple. He rose from his seat and smashed his hand down so heavily upon the table that his aide, busily engaged in writing, jumped back in fright. Turning to the lieutenant, he thundered: "That 's your spy-that paper! How many times have I ordered you to suppress it! Go and find it, and bring the owner of it to me! I have said so! Obey!"

His rage was fully justified, and in his heart Bob was laughing. “La Libre Belgique" was a Belgian newspaper that had been published secretly in Brussels ever since the invasion. A reward of five thousand, then ten, and finally fifteen, thousand dollars, had been offered to any one whose information would lead to the discovery of the editor and printer of it.

But the search had been in vain. Order after order had been issued to suppress it, but the sheet continued to appear more or less regularly, and was secretly distributed among the Belgians. The utmost effort of the German intelligence bureau had failed to unearth it.

In intimating that "La Libre Belgique" was the source of his information, Bob had effectually diverted suspicion from himself. A few minutes later he was dismissed and released; but as he left the prison and made his way outside, he was conscious of peering eyes following him. Were his footsteps shadowed by a spy for the purpose of locating what was more important to the German commandant-the discovery of the secret printing-place of the defiant newspaper? Bob smiled at the thought, and continued on his way to his cousin's home.

CHAPTER VI

THE MYSTERY OF THE CHATEAU

EGMONT greeted Bob's coming with demonstrations of joy, for, all night long, not once had he closed his eyes in sleep.

"How did you escape, Bob?" he demanded.

"They let me go," was the laughing reply, "just as I expected. That young prig of a lieutenant had nothing on me."

"But tell me what happened," asked Egmont eagerly.

In a few words Bob related the incidents of the examination before the commandant, and then added: "That is n't the first time 'La Libre Belgique' has helped our people in trouble. I wonder who publishes it, and how they manage to do it. Every German officer and private is on the lookout for the editor.”

"Whoever he is, he 's a great patriot!" replied Egmont, enthusiastically. "I'd like to congratulate him."

"Perhaps it's just as well we don't know him," mused Bob. "I have reasons to believe that I 'm being shadowed, Egmont. They think I know the editor and where the paper is published. That's why they let me off so easily. It was a ruse to make a bigger capture."

"Then we'd better keep away from our meeting-place for a few days. They might trace us to the abandoned sewer."

"Yes, we'll keep out of it for the present. Pass the word around to the boys that we 're being watched. We might make a trip outside the city, just to throw them off the trail. Let's see-can't we visit that ruined château near Laeken? I 've always wanted to see it. There's no German guard there now. It will be a

sort of vacation in the country."

"Yes, but the Germans are at Laeken itself, at the king's summer palace. We don't want to go near that."

"I'll keep away from them. I've had enough of their company to last me for some time."

Laeken was a short distance from the suburbs of Brussels, and was noted chiefly as being the seat of King Albert's summer palace, perched on a hill overlooking the city. It was an imposing building of gray stone in the Renaissance style. The greenhouses surrounding it were erected by King Leopold, and before the war they were considered the largest and finest in Europe. One could stroll for miles through glass-covered walks.

The German high command had taken possession of the summer palace, and many of the greenhouses had been dismantled or

completely destroyed; but it was still an imposing and wonderful place. Beyond the splendid park of Laeken stretched a series of beautiful châteaus. One of these dated back several centuries, and its ruins were frequently visited by travelers.

Bob and Egmont, having decided to make a day of it in the country, they invited Guy to accompany them, and set out on their expedition early the following morning.

Once more they were care-free, rollicking boys, with no more serious thought on their minds than that of having a good time. They carried fish-lines and hooks in their pockets, although fishing was "streng verbotten"-strictly forbidden-in any of the streams or lakes by order of the German high command. But there was always the chance of slyly dropping a line in some obscure pool or hole and hauling out a good fish. The very fact that it was forbidden by the enemy of their country added zest and temptation to the sport.

bris, they made their way into what had been the main hall of the château. Here an old pair of stone steps, in a better state of preservation than the walls, led downward, and the boys, bent on exploration, de

The old ruins of the château were several miles beyond the king's summer palace, and outside of the park that inclosed it. Egmont knew a short cut across the fields and through the woods, which enabled them to reach it without encountering any sentries. Once among the trees they felt reasonably safe from prying eyes and soon reached the château. After making a thorough investigation of the once turreted walls, and the moat surrounding them, now filled in with de

scended them, carefully picking their way. At the bottom they came to a cellarlike room, with sagging walls and half-demolished ceiling. They made their way gingerly across this to an arched passageway that seemed to lead still farther into the heart of the château.

"Where does this go?" asked Bob, peering into the dimness.

"There was an old dungeon down here," replied Egmont, "where they used