nd here, by this amazing piece of good luck, is the one
key for this very lock, and the man who had it is detained in hospital.
Come, I'm off to see him. Insensible, you say, when you left?"

"Yes," I answered, "and likely to be so for some time, McCarthy thinks;
so you probably won't get much information out of him just yet. But the
cypher----"

"I'll examine the cypher as I go along, I think. But I should like to
take a look at the man, at any rate, even if he can't tell me anything.
Will you give me a note to your friend McCarthy?"

"Of course," I answered, readily, and sat down to scribble the few lines
necessary to introduce Hewitt.

When I had finished, Hewitt, who had been examining the cryptogram
meanwhile, remarked: "This cypher is something out of the common,
Brett. I certainly don't expect to be able to read it in the
cab-journey--perhaps not in a week of study. The man who devised this is
a man of abilities altogether beyond the average."

"I have had my best try at it," I said, "but it beats me wholly. I
brought it purely as a matter of curiosity, to show you; it was the
merest chance that I brought the key as well."

"And if you hadn't I should probably have put the cypher aside until the
case was over, and so have missed the whole thing. Another lesson never
to despise what seem like trifles. If you have studied the cypher you
have no doubt observed--but there, we'll talk that over afterwards, and
the whole case if you like. I'll go now, and I'll tell you all about the
business when time permits."

II

Here is the case of the bond robbery as it had been presented to Martin
Hewitt that morning, while I was at St. Augustine's Hospital, and as I
learned it from him later. I had been a little puzzled to hear Hewitt
say that the case had seemed so desperately hopeless that he advised the
calling in of the police, because my experience had rather been that it
was Hewitt who was commonly called in--often too late--when the police
were beaten, and I had never before heard of a case in which this order
of things was reversed. It turned out, however, as will be seen, that in
the state of the matter as it first presented itself the only measures
that seemed possible were such as it was in the power of the police
alone to adopt.

Messrs. Kingsley, Bell, and Dalton were an old-established firm of
brokers whose operations were not enormous nor much in the eye of the
public, but who carried on a stead