inexplicable. But there was nothing exciting enough, in the statutes or
reports of court decisions or text-books, to cover up the questions
against which I had been beating in vain ever since I had entered this
accursed city.

An hour passed, and no Doddridge Knapp. It was long past office hours.
The sun had disappeared in the bank of fog that was rolling up from the
ocean and coming in wisps and streamers over the hills, and the light
was fast failing.

Just as I was considering whether my duty to my employer constrained me
to wait longer, I caught sight of an envelope that had been slipped
under the door. I wondered, as I hastily opened it and brought its
inclosure to the failing light, how it could have got there. It was in
cipher, but it yielded to the key with which Doddridge Knapp had
provided me. I made it out to be this:

"Come to my house to-night.
Bring your contracts with you.
Knapp."

I was thrown into some perplexity by this order. For a little I
suspected a trap, but on second thought this seemed unlikely. The
office furnished as convenient a place for homicidal diversions as he
could wish, if these were in his intention, and possibly a visit to
Doddridge Knapp in his own house would give me a better clue to his
habits and purposes, and a better chance of bringing home to him his
awful crime, than a month together on the Street.

The clocks were pointing past eight when I mounted the steps that led