f the
house, hoping to find another entrance. There was evidently a servants'
entrance at the back, leading from the lane, but this too was closed.
Throwing his light up, he saw that there was no broken glass on top of
the wall, as there had been in the front of the house, and, making a
jump, he caught the stone coping and drew himself up and astride.

He dropped into the darkness on the other side without any discomfort to
himself, and made his cautious way towards the house. Dogs were the
danger, but apparently Mrs. Rider did not keep dogs, and his progress was
unchallenged.

He saw no light either in the upper or lower windows until he got to the
back. Here was a pillared-porch, above which had been built what appeared
to be a conservatory. Beneath the porch was a door and a barred window,
but it was from the conservatory above that a faint light emanated. He
looked round for a ladder without success. But the portico presented
no more difficulties than the wall had done. By stepping on to the
window-sill and steadying himself against one of the pillars, he could
reach an iron stanchion, which had evidently been placed to support the
framework of the superstructure. From here to the parapet of the
conservatory itself was but a swing. This glass-house had casement
windows, one of which was open, and he leaned on his elbows and
cautiously intruded his head.

The place was empty. The light came from an inner room opening into the
glass sheltered balcony. Quickly he slipped through the windows and
crouched under the shadow of a big oleander. The atmosphere of the
conservatory was close and the smell was earthy. He judged from the
hot-water pipes which his groping hands felt that it was a tiny winter
garden erected by the owner of the house for her enjoyment in the dark,
cold days. French windows admitted to the inner room, and, peering
through the casement curtains which covered them, Tarling saw Mrs.
Rider. She was sitting at a desk, a pen in her hand, her chin on her
finger-tips. She was not writing, but staring blankly at the wall, as
though she were at a loss for what to say.

The light came from a big alabaster bowl hanging a foot below the ceiling
level, and it gave the detective an opportunity of making a swift
examination. The room was furnished simply if in perfect taste, and had
the appearance of a study. Beside her desk was a green safe, half let
into the wall and half exposed. There were a few prints hangi