him, here was a golden opportunity. But how were we to do this? We
discussed it, and discussed it, times out of number, but in vain. That
he must be stopped on his way down the street need not to be argued at
all. In what way, however, could this be done? The window was out of the
question, the door was not to be thought of; in that case the only
communicating place would be the small pipe by my side. But as I have
already pointed out, by reason of the elbow it would be clearly
impossible to force a message through it. All day we devoted ourselves
to attempts to solve what seemed a hopeless difficulty. Then like a
flash a brilliant inspiration burst upon me.

"By Jove, I have it!" I said, taking care to whisper lest any one might
be listening at the door. "We must manage by hook or crook to catch a
mouse _and let him carry our appeal for help to the outside world_."

"A magnificent idea! If we can catch one I do believe you've saved us!"

But to catch a mouse was easier said than done. Though the room was
alive with them they were so nimble and so cunning, that, try how we
would, we could not lay hold of one. But at length my efforts were
rewarded, and after a little struggle I held my precious captive in my
hand. By this time another idea had come to me. If we wanted to bring
Nikola and his gang to justice, and to discover their reason for
hatching this plot against us, it would not do to ask the public at
large for help--and I must own, in spite of our long imprisonment, I was
weak enough to feel a curiosity as to their motive. No! It must be to
the beggar who passed the house every morning that we must appeal.

"This letter concerns you more than me," I said to my fellow-prisoner.
"Have you a lead pencil in your pocket?"

He had, and immediately threw it across to me. Then, taking a small
piece of paper from my pocket, I set myself to compose the following in
French and English, assisted by my companion:--

"If this should meet the eye of the individual to whom a young
Englishman gave half a sovereign in charity three weeks ago, he is
implored to assist one who assisted him, and who has been imprisoned
ever since that day in the room with the blank wall facing the street
and the boarded-up window on the right-hand side. To do this he must
obtain a small file and discover a way to convey it into the room by
means of the small pipe leading through the blank wall into the street;
perhaps if this could be dislodged