e
staircase I thought I heard some one coming. My nerves were going
anyhow, there in the dark, and I could scarcely stand. I got up as far
as the third or fourth step; then I felt that some one was coming
toward me on the staircase. The next instant a hand met mine on the
stair-rail. Some one brushed past me, and I screamed. Then I must
have fainted."

That was Louise's story. There could be no doubt of its truth, and the
thing that made it inexpressibly awful to me was that the poor girl had
crept down to answer the summons of a brother who would never need her
kindly offices again. Twice now, without apparent cause, some one had
entered the house by means of the east entrance: had apparently gone
his way unhindered through the house, and gone out again as he had
entered. Had this unknown visitor been there a third time, the night
Arnold Armstrong was murdered? Or a fourth, the time Mr. Jamieson had
locked some one in the clothes chute?

Sleep was impossible, I think, for any of us. We dispersed finally to
bathe and dress, leaving Louise little the worse for her experience.
But I determined that before the day was over she must know the true
state of affairs. Another decision I made, and I put it into execution
immediately after breakfast. I had one of the unused bedrooms in the
east wing, back along the small corridor, prepared for occupancy, and
from that time on, Alex, the gardener, slept there. One man in that
barn of a house was an absurdity, with things happening all the time,
and I must say that Alex was as unobjectionable as any one could
possibly have been.

The next morning, also, Halsey and I made an exhaustive examination of
the circular staircase, the small entry at its foot, and the card-room
opening from it. There was no evidence of anything unusual the night
before, and had we not ourselves heard the rapping noises, I should
have felt that Louise's imagination had run away with her. The outer
door was closed and locked, and the staircase curved above us, for all
the world like any other staircase.

Halsey, who had never taken seriously my account of the night Liddy and
I were there alone, was grave enough now. He examined the paneling of
the wainscoting above and below the stairs, evidently looking for a
secret door, and suddenly there flashed into my mind the recollection
of a scrap of paper that Mr. Jamieson had found among Arnold
Armstrong's effects. As nearly as possible I repe