When I had done with them I got out Scudder's little black
pocket-book and studied it. It was pretty well filled with jottings,
chiefly figures, though now and then a name was printed in. For
example, I found the words 'Hofgaard', 'Luneville', and 'Avocado'
pretty often, and especially the word 'Pavia'.

Now I was certain that Scudder never did anything without a
reason, and I was pretty sure that there was a cypher in all this.
That is a subject which has always interested me, and I did a bit
at it myself once as intelligence officer at Delagoa Bay during the
Boer War. I have a head for things like chess and puzzles, and I
used to reckon myself pretty good at finding out cyphers. This one
looked like the numerical kind where sets of figures correspond to
the letters of the alphabet, but any fairly shrewd man can find the
clue to that sort after an hour or two's work, and I didn't think
Scudder would have been content with anything so easy. So I
fastened on the printed words, for you can make a pretty good
numerical cypher if you have a key word which gives you the
sequence of the letters.

I tried for hours, but none of the words answered. Then I fell
asleep and woke at Dumfries just in time to bundle out and get into
the slow Galloway train. There was a man on the platform whose
looks I didn't like, but he never glanced at me, and when I caught
sight of myself in the mirror of an automatic machine I didn't
wonder. With my brown face, my old tweeds, and my slouch, I was
the very model of one of the hill farmers who were crowding into
the third-class carriages.