"Which reached its destination in due course?"

"So I hear this morning. But how on earth--"

"Easily enough. The whole thing gets slipped into a larger open envelope,
the kind of big-mouthed affair that enterprising firms send out circulars
and patterns with. This falls into the hands of the woman who is at the
bottom of this and every other case, and she reads the synopsis from
sheer curiosity. The case fits her case, and there you are. Mind you, I
don't say that this is how the thing actually happened, but how it might
have done so. When did you post the letter?"

"I can't give you the date. Say ten days ago."

"And there would be no hurry for a reply," Bell said, thoughtfully. "And
you had no cause for worry on that head. Nor need the woman who found it
have kept the envelope beyond the delay of a single post, which is only a
matter of an hour or so in London. If you go a little farther we find
that money is no object, hence the L1,000 offer and the careful, and
doubtless expensive, inquiry into your position. Steel, I am going to
enjoy this case."

"You're welcome to all the fun you can get out of it," David said,
grimly. "So far as I am concerned, I fail to see the humour. Isn't this
the office you are after?"

Bell nodded and disappeared, presently to return with two exceedingly
rusty keys tied together with a drab piece of tape. He jingled them on
his long, slender forefinger with an air of positive enjoyment.