or the maids and Mrs. Klopton always
lock themselves beyond reach of the bell at night, and put on a
dressing-gown. The bell rang again on my way down-stairs. I lit the hall
light and opened the door. I was wide-awake now, and I saw that it was
Johnson. His bald head shone in the light--his crooked mouth was twisted
in a smile.

"Good Heavens, man," I said irritably. "Don't you ever go home and go to
bed?"

He closed the vestibule door behind him and cavalierly turned out the
light. Our dialogue was sharp, staccato.

"Have you a key to the empty house next door?" he demanded. "Somebody's
in there, and the latch is caught."

"The houses are alike. The key to this door may fit. Did you see them go
in?"

"No. There's a light moving up from room to room. I saw something like
it last night, and I have been watching. The patrolman reported queer
doings there a week or so ago."

"A light!" I exclaimed. "Do you mean that you--"

"Very likely," he said grimly. "Have you a revolver?"

"All kinds in the gun rack," I replied, and going into the den, I came
back with a Smith and Wesson. "I'm not much use," I explained, "with
this arm, but I'll do what I can. There may be somebody there. The
servants here have been uneasy."

Johnson planned the campaign. He suggested on account of my familiarity
with the roof, that I go there and cut off escape in that direction. "I
have Robison out there now--the patrolman on the beat," he said. "He'll
watch below and you above, while I search the house. Be as quiet as
possible."

I was rather amused. I put on some clothes and felt my way carefully
up the stairs, the revolver swinging free in my pocket, my hand on the
rail. At the foot of the ladder I stopped and looked up. Above me there
was a gray rectangle of sky dotted with stars. It occurred to me that
with my one serviceable hand holding the ladder, I was hardly in a
position to defend myself, that I was about to hoist a body that I am
rather careful of into a danger I couldn't see and wasn't particularly
keen about anyhow. I don't mind saying that the seconds it took me to
scramble up the ladder were among the most unpleasant that I recall.

I got to the top, however, without incident. I could see fairly
well after the darkness of the house beneath, but there was nothing
suspicious in sight. The roofs, separated by two feet of brick wall,
stretched around me, unbroken save by an occasional chimney. I went very
softly over to th