BBFVVZBJAHKL

The translator of the cipher message simply reverses this proceeding. He
knows the key-word, and he writes it above the cipher message:

INTHEINNINTH
BBFVVZBJAHKL

He traces the I column until B is reached; the _first_ letter in that
line, T, is the first letter of the message--and so on.

Simple! Yes, childishly simple with the key-word; and the key-word can
be carried in one's mind. Without the key-word, translation is
impossible.

Harleston put down the paper and leaned back.

Altogether it was a most interesting collection, these four articles on
the table. It was a pity that the cab and the sleeping horse were not
among the exhibits. Number one: a lady's lace handkerchief. Number two:
three American Beauty roses, somewhat the worse for wear and violent
usage. Number three: a cipher message. Number four: photograph of
Madame--or Mademoiselle--de Cuthbert, de Spencer, de Lotzen. There was a
pretty plot behind these exhibits; a pretty plot, or he missed his
guess. It might concern the United States--and it might not. It would be
his duty to find out. Meanwhile, the picture stirred memories that he
had thought long dead. Also it suggested possibilities. It was some
years since they had matched their wits against each other, and the last
time she rather won out--because all the cards were hers, as well as the
_mise en scène_. And she had left--