iplomatic report, written in an enemy country, as the
three mystery cities of the world. The first one is in Germany, and I
have already explored it. I have information, but information which
without its sequel is valueless. Kroten is the second. Ten years ago it
was a town of eighteen thousand inhabitants. To-day there are at least
two hundred thousand people there, and it is growing all the time."

"Say, how can a town of that size," Chalmers enquired, "be termed a
mystery city in any sense of the word? Travelling's free in Russia. I
guess any one that wanted could take a ticket to Kroten."

"A good many do," Jesson assented calmly, "and some never come back.
America and Russia are on friendly terms, yet two men in my branch of
the service--good fellows they were, too--started out from Washington
for Kroten six months ago. Neither of them has been heard of since;
neither ever will be."

"How's it done?" Chalmers asked curiously.

"In the first place," Jesson explained, "the city itself stands at the
arm of the river, in a sort of cul-de-sac, with absolutely untraversable
mountains on three sides of it. All the roads have to come around the
plain and enter from eastwards. There is only one line of railway, so
that all the approaches into the city are easily guarded."

"That's all right geographically, of course," Nigel admitted, "but what
earthly excuse can any one make for keeping tourists or travellers out
of the place if they want to go there?"

"That is perhaps the most ingenious thing of all," Jesson replied. "You
know that Russia is now practically a tranquil country, but there are
certain bands of the extreme Bolshevistic faction who never gave in to
authority and who practically exist in the little-known places by means
of marauding expeditions. The mountains about Kroten are supposed to
have been infested by these nomadic companies. Whether the outrages set
down to them are really committed or not, I don't suppose any one knows,
but my point of view is that the presence of these people is absolutely
encouraged by the Government, to give them an excuse for the most
extraordinary precautions in issuing passports or allowing any one from
the outside world to pass into the city. If you get in, I understand you
are waited upon by the police within half an hour and have to tell them
the story of your past life and your future intentions. After that you
are allowed to go about on parole. If you get too inquisiti