nd is free."

"That, gentlemen, is my explanation of what happened in the house
today. Of course, it is largely theory, but I believe it fits the
case uncommonly well."

"I'll say you're there!" cried Tierney.

"Yes," Morgan agreed. "You talk as if you had been a spectator of
the whole occurrence. I doubt if a clearer explanation could be
made, and I think you came pretty near the truth when you said a
little while ago that we actually had uncovered something today.
There is still a mystery of some kind, but thanks to you, we are now
in a position to take some definite steps toward solving it."

"Still, there is one illogical point in your surmise. The letter
from St. Louis arrived sometime this morning. If Atwood was in
Chicago Tuesday morning, how did he get that letter off, so
quickly?"

"The trouble with an analysis based chiefly on speculation, Morgan,
is that many points may seem illogical and unexplained. We can only
rely definitely upon the outstanding features. However, I never
adopt any explanation unless it has a basis in possibility. You
remember that a while ago I told you I thought that shot was a
mistake--that it was never intended a shot should be fired. Whoever
was engaged in that occurrence knew that the shot would lead to a
police investigation, and once the police start, there is no telling
where the matter may end. To head them off quickly, is it not
possible that someone left immediately for St. Louis to post that
letter?"

Morgan nodded. "It's straining a point, but it's quite possible,
Marsh. At least, we have no better explanation."

They had finished their meal, and after Marsh settled the bill,
parted on the sidewalk; Marsh to return to his apartment and await
developments there, while Morgan and Tierney undertook some
investigations which Morgan had in mind.

On his return to the house, Marsh noted with satisfaction that a
policeman in uniform was already on duty. However, he wanted to make
sure that the girl was all right, so instead of going directly to
his apartment, he continued on up the stairs to the Atwood apartment
and rang the bell. After a slight pause, Miss Atwood opened the
door. Her eyes were red with weeping, and she held her handkerchief
so as to partly conceal her face.

"I called to see if everything was all right," explained Marsh.
"Why, what has happened?"

He knew perfectly well the cause of the girl's trouble, and he had
to struggle hard to assume an air of