'That the thing is un fait accompli. I feel certain that what I say is correct, and that we are literally sealed up here like sardines in a tin. Otherwise, the atmosphere would not be so insufferably close. You see the gravity of the situation?'

Armand shrugged his shoulders.

'It is not lost upon me,' he said. Fortunately, the suspense will not be unduly prolonged. We shall soon know.'

Both trains were moving slowly on. Calculating by moments, the cars should not have been remote from the exit over against Joinville. And yet, hanging anxiously over the side, the two Englishmen could discern nothing beyond the purple, shot dark

ness.

There was no circular focus of light, no welcome rays penetrating the exit from the tunnel. Either some calamity had happened, or they were the victims of a cruel misfortune.

'The exit is assuredly blocked up,' Eustace muttered.

Armand's reply was unheard. The pilot train, forging slowly ahead, bumped and clattered, the trucks came thudding together along its entire length, and then finally came to a standstill.

'For heaven's sake shut off steam there, or you will be into us,' came a harsh voice from the pioneers. There is something on the line.'

The second train also came to its brakes. Armand hastened to the scene of the trouble. The young German in charge of the other transport was already examining his surroundings with the aid of a lantern.

'What has happened?' Armand asked, anxiously.

The whole line is strewn with masonry,' was the reply. 'Look for yourself, and see if it is not so, Monsieur le Capitaine.' Armand took the lantern which the other proffered, and flashed its sickly yellow rays upwards. Not only was the line strewn with masses of rock and earth and twisted brickwork, but the serried mass rose upward till roof and floor came together. Huddlestone had guessed it. Both exits from the tunnel had been destroyed.

'A most amazing thing,' Armand cried. A marvellous coincidence.' The young German smiled somewhat grimly.

'I guessed this,' he said, though I had no need to tell you. It becomes necessary to go back in the direction of Orloy.'

'Into the hands of your countrymen, who have doubtless regained the lost ground there,' Armand said, dryly. My friend,

to prevent accidents I contrived to seal up the entrance of this tunnel after my train entered.'

6

Then we are caught like rats in a pipe.'

'So it seems. But can you inform me how my brilliant scheme came to be so speedily pirated as this?'

'That is merely conjecture,' the youthful German replied. 'I only know that my train was headed back by troops two miles this side of Joinville. They were in force, and I feared derailment. For the time, at any rate, the valley seems to have fallen into your hands. The enemy bore me back into the tunnel, and that is all I know. The position is anything but a pleasing one.'

Armand agreed sullenly. He understood perfectly what had happened. A body of troops had made a dash for Joinville, and they had destroyed a portion of the tunnel, with a view to checking any advance on the part of General Deganfeld. By an amazing chance, both exits had gone simultaneously.

Apparently there was nothing to be done but sit down and endure it. Sooner or later the Bavarian advance from Marlay must result in communications being opened up again. But Deganfeld was by no means over strong, and a large French force -the force Armand was so anxious to touch-hovered menacingly in the country about Joinville.

Under these circumstances, many days might elapse before the tunnel was cleared. That Deganfeld would make desperate efforts to do so was certain. That the French would do their best to prevent him was inevitable. To force the obstacle from within, aided by a mere handful of men without tools, was practically impossible.

6

And we are without stores,' said Armand. 'We might hold out for a couple of days. Major, your cases are

9

'Not mine,' Eustace said, hurriedly. 'Besides, we cannot get
much nourishment out of surgical appliances.
shall perish miserably ere long for want of air.
is insufferable.'

In any case, we
The atmosphere

of

Eustace spoke truly. The air was hot and heavy, a sense languor and fatigue lay upon every man there. As yet, they hardly realised the full extent of the danger. Unless relief came speedily, a horrible death lay before them. The black darkness was in itself a terror.

'Something must be done,' Armand said, hoarsely. Come, is there not one of you who can suggest anything?'

The young German officer touched Armand's elbow. 'There is one desperate chance,' he said. 'If you follow me, I will show you the way.'

'Lead on,' said Armand. 'Nothing can be more desperate than this.'

CHAPTER III.

LANTERN in hand, the German plunged forward. He was followed by Armand, together with the Englishmen. No word was spoken on either side, the journey being undertaken in grim silence. At some distance from the trains and the troops the air was a little less vitiated, and oppressed lungs drew breath more freely. At the end of a mile the guide paused.

'Do you notice anything?' he asked.

They all had, almost at the same moment. They noticed a purer, cooler air, like champagne to their jaded senses.

'And there seems to be an absolute draught,' said Huddlestone.

"

'Hardly that,' said the German. It has gone again. Half a dozen men might manage to exist here for a time, but no more.' "I can't understand whence comes the air,' said Armand.

'It seems to me that we Germans know your country better than you know it yourselves,' said the other, with a dryness that brought the blood to Armand's cheek. But that is by the way. As a matter of fact, we are exactly under the ventilating shaft of the tunnel. It passes through the hill, rising to a round tower of stone beyond-a capital landmark.'

slimy walls of the tunnel. Presently he found what he wanted-a square wooden trap, which he proceeded to pull away from the wall. This done, a hole barely large enough for a man to squeeze into was disclosed.

'More charming than it seems,' the German explained. 'The semi-circular pipe leads on to the roof of the tunnel. There is an iron grating above us, if you will take the trouble to look.'

Sure enough, as the lantern's rays flashed on the roof, a rusty, sooty grating came in the line of light. Like a cat, the German wriggled himself into the hole, pushing his lantern before him, the others following.

It was a dusty, dingy, horrible, choky business, resulting in hands and faces being smothered in soot and cinders, but it was accomplished at last. When, finally, the four adventurers stood on the grating, they could see the brilliant shield of the blue sky far above them as a cerulean circle clear cut by the funnel, and they could breathe again.

The pure frosty air ran like quicksilver along Armand's veins. 'It is good to live, after all,' he cried. Still, there is much to be done. Herr Lieutenant, how do you propose to reach the summit?'

The way is provided, sir."

'Nothing easier,' said the other. A flight of iron ladders led upwards. It was a long and tedious business, for the shaft was many hundreds of feet through the heart of the hill, and the ladders were of iron and absolutely perpendicular.

The intense cold struck, even down there. Each of the adventurers could feel the chill grip of the metal as it struck through their gloves. As they toiled up, foot by foot, the pace gradually slackened. It was fortunate, perhaps, that darkness reigned supreme, and thus veiled the real danger of the undertaking.

'I'm glad I can't see anything,' Huddlestone panted. Looking down from a height always makes me confoundedly giddy. And we must be up

'Don't think of it,' Eustace replied. I'm trying not to, and I never was in such a blue funk in all my life. Sebastopol was nothing to this.'

All things come to an end, and the weary climb was over at last. When the four reached the top of the shaft a brief terror

awaited them. Over the entire surface a network of iron com pleted the semblance of a cage.

'Good heavens!' Huddlestone groaned. 'Have we come all this way to be baffled like this! How maddening!'

Armand swore volubly. Then annoyance took the place of anger, as the German reached up and lifted the centre of the grill. The latter seemed to know perfectly well that the grill possessed a swinging doorway.

'It is the way we have beaten you all along,' he said. 'We know everything, you know nothing-except how to fight.'

Armand turned away bitterly mortified. The truth stung like a whiplash. Ere he could think of a suitable reply, the boom of a gun, followed by the quick rattle of musketry fire, smote on the ear. Evidently, sharp work was in progress down in the valley towards Joinville.