ched it his heart leaped, for
the object was a key--obviously the key of one, or both, of the doors.

He fitted it cautiously into the lock of the right-hand door and turned
it gently, and with a soft click the wards fell back and the door jarred
slightly open.

Without wasting a moment, Frobisher pulled it wide and stepped outside,
exulting in his new-found liberty. But, alas! his exultation was only
momentary. An instant later he realised the cruel hoax that had been
played on him, for extending over a distance of many yards in every
direction was a sort of pavement of broken glass, pointed and keen-edged
as a forest of razors. The glass had been so firmly fixed in the ground
that it was impossible to remove it; and Frobisher instantly realised
that his escape that way was most effectually barred. Even with strong
boots on, it would have been a difficult enough matter to traverse that
glass-strewn patch without cutting one's feet to pieces; and with feet
merely protected by thin wrappings of wool and linen, the thing was an
impossibility.

This, then, was the meaning of the removal of his boots; and, as he
realised the sardonic cruelty of the men who could invent such a device
for tormenting a prisoner, his heart almost failed him. It seemed as
though he were doomed to remain for ever immured in this horrible place.

CHAPTER THIRTEEN.

PURSUED BY BLOODHOUNDS.

With a smothered ejaculation of bitter disappointment Frobisher recoiled
a few steps in sheer despair, bringing up rather sharply against the
iron-plated door through which he had just emerged; and the next instant
he realised that he was doubly trapped. Escape was cut off in front of
him by that broken glass, and he had been in such haste to _get away_
from his prison that he had never thought of removing the key from the
inside of the door, or of taking precautions to prevent the door from
closing behind him and cutting off his retreat, as it had done.

Retreat, after he was once clear of the walls, had naturally never
entered his mind. But now he would have been glad enough to have been
able to return to his cell unobserved. It would be intensely
humiliating to be obliged to wait there, in the small space between the
door and the glass-sown path, until his jailer arrived, some twenty-four
hours later, to release him. Yet there seemed to be no alternative.

How careless, how criminally foolish he had been to allow himself to be
trapped by