when their hopes were practically extinguished,
the last chests removed disclosed a little oaken door set into the wall,
not more than four feet high by three feet broad. Drake was about to
open it impulsively when Frobisher restrained him. He did not want
either of them to be killed on the very threshold of success by some
other hidden and fiendishly ingenious piece of mechanism. But when
cautiously opened with the aid of one of the sticks, nothing happened in
this instance, and they crawled safely through into another passage,
being careful to close the door behind them.

This passage looked a good deal more promising, there being no less than
four other corridors branching off it at right angles, each, curiously
enough, leading away to the left. But they determined to go straight
ahead in the first instance, exploring the corridors afterwards, if not
successful in their present direction. They traversed so long a
distance in a perfectly straight line, the ground rising gently all the
way, that they soon became convinced that they were at last on the right
track, as the passage must, some distance back, have passed from under
the foundations of the palace itself, and be leading, undoubtedly, to
some exit at a considerable distance from the building. It seemed
probable that it might have been constructed with a view to providing a
means of escape, should the palace ever be attacked and stormed.

That they were correct in their surmise was proved shortly afterward
when, a little distance ahead, Frobisher caught sight of a pin-hole of
light. This presently resolved itself into sunlight shining through the
keyhole of another door; and they realised that, since it was now broad
daylight, they must have spent several hours in Genghiz Khan's
treasure-house. The door did not open with a handle, as the others had
done, and there was no key hanging handily on the wall, as there had
been when Frobisher escaped out of the pirate fortress; so that, after
all, there was still a rather formidable obstacle to be overcome before
they could actually stand in the blessed light of day again.

"We must not let this stop us, Drake," exclaimed Frobisher; "though I
don't yet quite see what we are to do. If we had a big stone we could
burst the lock off, or out; but there isn't so much as a pebble to be
seen anywhere about."

"How far are we away from the palace, do you think?" asked Drake. "If
we are out of earshot of the pirat