d there, indeed, they were, prisoners, with what fate in store none of
them could say.

Suddenly from the darkness a sentinel challenged in German, and the
captain of the little party answered, passing on with the prisoners.

A little later they turned down into a sort of trench and went along
this, the boys being so placed that each walked between two Germans,
who carried their guns with bayonets fixed, as though they would use
them on the slightest provocation. But Blake and his chums gave none.

And then, making a sudden turn, the party came to what was evidently an
outpost of importance. There were several large underground chambers,
fitted up with some degree of comfort and a number of officers and
soldiers about. Some were eating, some smoking, and others drinking, and
still others sleeping. In one room could be seen a rough table, laden
with maps and papers, and there were many electric lights, showing to
what degree of perfection the German military system was carried out at
this point. A portable dynamo and gasolene engine probably furnished the
current.

The captives were halted, and a brief talk in German took place between
the captain and the officer to whom he reported. What was said Blake and
his chums could not, of course, hear, nor could they have understood had
they heard.

A little later, however, they were ordered to march on, and then were
shown into an underground room, none too clean and quite dark, and the
door was banged shut on them. Just before this they had seen Secor and
Labenstein go off in another direction, still carrying the boxes of
films.

The echoes of the retreating footsteps of the men who had thrust them
into their prison soon died away, and the boys were left to themselves
in a veritable cell that was unpleasantly dirty and dark.

"Whew!" whistled Joe, after a moment of silence. "This time we certainly
are up against it!"

Suddenly a light flashed in the darkness.

"What's that?" asked Joe sharply.

"I want to see what sort of hotel accommodations they've given us," was
Blake's grim answer, as he flashed his pocket light about. The Germans
had not taken those from the boys, and they were soon inspecting their
prison.

It was merely a hole dug underground, earth, supported by timbers,
forming the floor, ceiling and sides, while the entrance was made of a
plank door, with cracks large enough to show that a passage ran
outside--a passage along which men passed with a fre