what that
envelope postmarked 'Brooklyn' contained?"

"Oh, but I do!" Emily exclaimed. "Father had thrust it in the stove,
but the fire had gone out, without his noticing it. I found it the
next morning, when I raked down the ashes."

"You--read it?" Morrow carefully steadied his voice.

"No," she shook her head, with a faint smile. "That's the queer part
of it all. No one could have read it--no one who did not hold the key
to it, I mean. It was written in some secret code or cipher, with
oddly shaped figures instead of letters; dots and cubes and
triangles. I never saw anything like it before. I couldn't understand
why anyone should send such a funny message to my father, instead of
writing it out properly."

"What did you do with the letter--did you destroy it?" This time the
detective made no effort to control the eagerness in his tones, but
the girl was so absorbed in her problem that she was oblivious to all
else.

"I suppose I should have, but I didn't. I knew that it was what my
father had intended, yet somehow I felt that it might prove useful in
the future--that I might even be helping Father by keeping it, against
his own judgment. The envelope was partially scorched by the hot
ashes, but the inside sheet remained untouched. I hid the letter
behind the mirror on my dresser, and sometimes, when I have been quite
alone, I took it out and tried to solve it, but I couldn't. I never
was good at puzzles when I was little, and I suppose I lack that
deductive quality now. I was ashamed, too: it seemed so like prying
into things which didn't concern me, which my father didn't wish me to
know; still, I was only doing it to try to help him."

Morrow winced, and drew a long breath. Then resolutely he plunged into
the task before him.

"Emily, don't think that I want to pry, either, but if I am to help
you I must see that letter. If you trust me and believe in my
friendship, let me see it. Perhaps I may be able to discover the key
in the first word or two, and then you can decipher it for yourself.
You understand, I don't wish you to show it to me unless you really
have confidence in me, unless you are sure that there is nothing in it
which one who has your welfare and peace of mind at heart should not
see."

He waited for her reply with a suffocating feeling as if a hand were
clutching at his throat. A hot wave of shame, of fierce repugnance and
self-contempt at the role he was forced to play, surged up within