But even Dick, for all the wild mood of anger that had held him since he had had Hallo in his power, had to consent to a halt now. If the Servians planned not only to inflict a severe blow on the Austrians by the destruction of war material, but to spread terror as well, they succeeded admirably. For there was not one explosion alone; there was a series of explosions. And fire spread from the arsenal, too.

"The shells are going off, you see," said Dick, a little awed. "They're exploding in all directions. I suppose there will be a good deal of damage. And those cartridges must be sending an awful lot of bullets around promiscuously."

"I don't think many people will be hurt," said Hallo. Like Dick, he was awed by the spectacle, and the terrible magnificence of it for the moment seemed to have driven from his mind all thought of anything but the explosion itself. "There are very few houses about the arsenal; they are mostly public buildings of one sort and another. It's not the sort of neighborhood people choose to live in. Even in time of peace there may be an accident in an arsenal at any moment—and just as bad an explosion as this one."

But then, suddenly, Hallo seemed to remember his position.

"You will pay for this!" he cried. "It is your doing, because if you had let me go I should have stopped that! You are in league with the Servian spies who have been working here for months, who planned the murder of the Archduke in Serajevo—"

"Why don't you say I killed him?" suggested Dick. "Forward march, again! The show is over!"

"Oh, your time will come—and you will cry to me for help then! The police only had suspicions before, but now they will have facts, and all the consuls and ambassadors in the world won't be able to help you! It won't be a matter for the police at all, my lad! It will be a court-martial that will try you."

"Perhaps. We shall see. Hello, what's this?"

Dick had just been thinking to himself that it was highly fortunate that they had passed the settled district to the northeast of Semlin before the explosion, since he could easily imagine the outpouring there must have been into the streets at that terrific sound. But now there was a sound of rushing feet, and around a corner, perhaps a quarter of a mile in front of them, a body of men appeared—troops, coming at the double quick.

"Here, this way!" said Dick, sharply.

He pointed to a clump of trees beside the road, and forced the reluctant Hallo to go in before him. The pistol was giving him fine support for it was very evident that Hallo did not mean to take chances. Dick did not know, as a matter of fact, whether he would be able to fire if the necessity arose. To shoot even Mike Hallo in cold blood, and when the man was helpless to all intents, was something he could not contemplate without a shudder.

In fact it was partly because Hallo was his enemy that he felt that he was likely to hesitate, and at a moment when hesitation was likely to be dangerous, if not fatal.

"I'd feel differently if I didn't have anything against him, personally," said Dick to himself. "As it is, I'd never be sure, if I shot him, whether I was doing it in self-defence or because it was a good chance to get even with him for the things he's done to me and to my family."

Fortunately, however, Hallo did not put him to the test. Dick realized that it was a dangerous minute. The seconds that elapsed while the soldiers were passing in the road were the longest he had ever spent. A single shout from Hallo would have settled matters. In such times, and with a reminder of the dangers of the situation such as the destruction of the arsenal, there would have been an immediate investigation, and, whatever happened to Hallo himself, Dick would be in a bad case, and he fully realized his situation.

Dick allowed plenty of time for the soldiers to pass. It did not take long, as a matter of fact, and he decided that there could have been only a small detachment, not more than a company of infantry probably. Hallo might have told him that there were comparatively few troops in Semlin, and that the greater part of the Austrian forces along the border were placed at two points, Schabatz, on the Save, and Losnitza, on the Drina, since it was at those two points that the invasion of Servia was to be begun, according to the plan of the Austrian General Staff.

The bombardment of Belgrade was not intended to cover a subsequent attack, but to serve as a feint, in the hope that a large number of Servian troops would be retained for the defense of the capital. Belgrade was of no use to the Austrians. By holding Semlin they could cut the railway and had every advantage that the occupation of Belgrade could have given them, except the sentimental value of having possession of the enemy's capital. Later in the war the Austrians were to make the grave mistake of occupying Belgrade for just such sentimental reasons, and the mistake was to be proved by the sacrifice of an army.

"All right, we can go back to the road again," said Dick, when he had allowed more than enough time for a rear guard to pass. "Your friends have held us up. See if you can't move a little faster to make up for the delay!" and he prodded him with his revolver for emphasis.

Dick had scattered his corn steadily and now, as they went back to the road, he kicked the kernels that marked their digression aside, since he knew that Stepan and the others, if they were following, would only waste time by following the detour into the woods. He had brought a plentiful supply, and he was glad of it, since he was traveling further with Hallo than he had thought it at all likely that he could. For some time he had been listening eagerly for some indication that Stepan and his friends were approaching, but there had been none. He was not ready to be worried about them yet, however dangerous as he knew their work had been, since it was easy to imagine a dozen trifling things that might have delayed them.

And yet he could think of more serious things, too. There might have been a premature explosion of the mine, and he shuddered at the thought of what the fate of the Servians must have been if that was what had happened. Or they might have been caught as they emerged from the tunnel. Or—but he shook off such ideas. There was no reason yet to suppose that everything was not all right. And the important thing was to get Hallo to the boathouse. It was absolutely vital, now that Hallo knew about that refuge, and also the identity of his former office boy, that Hallo should not escape to use his knowledge, since he could do incalculable mischief to the cause that Dick had now made his own.

Hallo went along stumbling, groaning, growling. Finally Dick did begin to feel sorry for him. After all, the man was in bad condition. He had been painfully hurt by the crashing down of the big packing case, and his fright and escape through the water had weakened and tired him, even before that. Now he seemed to be in the last stages of exhaustion, and when he began to plead with Dick on account of his weariness, rather than with promises or threats, he was on the right track. Perhaps that feeling threw Dick off his guard for a moment. At any rate, when Hallo finally made his bid for freedom he chose the most, perhaps the only, opportune moment.

Dick had taken his eyes off him for a moment, and had loosened his hold on the butt of his automatic. And just then Hallo stopped suddenly, whipped back his foot, and tripped Dick neatly and successfully. Dick went down; before he could reach for the pistol, Hallo was on top of him. Exhausted though he was, Hallo outweighed Dick still as much as ever, and he was strong as well. Dick fought well, but the surprise had been complete. As he reached for the pistol, Hallo seized his arm and in a moment was twisting it around behind his back in a cruel hammer lock hold—that deadliest of wrestling grips, that means a broken arm for the victim unless he yields. The struggle was over in a moment, and the positions were now completely reversed.

Hallo had the pistol, and he was in as absolute command as Dick had been while he still held it.

"Ah!" said Hallo. "I said your time would come, Dick, my lad! And it has! You're in my power now! I could kill you, do you know that?"

Dick did not answer; he was thinking too hard. And there was nothing for him to say, anyhow. He had been neatly tricked, and, though he was badly frightened and ready to admit it to himself, it was impossible not to admire Hallo, so adroit had he been in seizing his one chance of escape.

"Yes, I could kill you easily enough," Hallo repeated. "And no one would blame me. I have proof that you are a spy, and it is a praiseworthy thing to kill a spy. But I shall not. I shall be generous to you, Dick, even if you did not remember our old friendship. I shall take you back with me, and turn you over to the soldiers, and they will try you fairly, and let the American consul defend you, and then they will shoot you."

A perfect frenzy of revenge seemed to seize the Hungarian as Dick maintained his silence.

"Oh, they will know how to make you talk!" he cried. "Keep still, then, if you like! I don't care! You would come here after me? You would try to make me pay back the money you say I took? Well, then, I did take it! And why not? I could use it better than your foolish family! Ah, Dick, it does not pay to monkey with the buzz-saw, as your father used to say! Does it? I am a buzz-saw—yes, that is what I am! Now, then, march! But turn the other way!"

"I'm not afraid of you," said Dick, breaking his silence at last and speaking in a contemptuous voice. "I think you're pretty brave, though, Mike. I didn't think so a little while ago. I thought you were a great coward. But if you have the courage to go to the army authorities after the destruction of the arsenal, you are a brave man, and I respect you for that, even if you are a thief!"

Hallo stared at him stupidly for a moment.

"Eh? What is that?" he said. "No matter! March! You are trying to bluff me, as you Americans say, and you cannot do it! They will know the truth when I tell them. They will believe me. They will not think that I had anything to do with that."

"You say so—but you don't believe what you're saying yourself," said Dick. "When they hear about how you have been going on, they will think it funny that you did not know about this plot in time to warn them. Do you think they will try us at the same time?"

But he stepped out, just the same, for Hallo was beginning to look dangerous. He looked frightened, too, and Dick felt that it was not at all certain that Hallo would force him to go all the way. When he had had time to think for a little of what the attitude of the Austrian commander was likely to be, Dick thought military headquarters in Semlin would be about the last place that he would seek!

Even so, however, there did not seem to be much to make Dick hopeful. For it was just as likely that Hallo would shoot him if he decided to stay away from Semlin as that he would let him go.

But then there came just the interruption for which Dick had prayed. Ahead of them appeared half a dozen figures walking swiftly, at their head a smaller man or boy, his eyes on the ground. Dick's heart gave a leap.

"Into the field there!" said Hallo, with a growl.

Dick obeyed, scattering the last kernels of corn. And five minutes later a wild rush, led by Stepan Dushan, caught them. Once more the tables were turned, and Hallo was a prisoner for the third time that night!