Mr. Sheldon the dentist sat up till the small hours that night, as
he had done for many nights lately. He finished his work in the
torture-chamber, and went up to the common sitting-room, or
drawing-room as it was called by courtesy, a little before midnight.
The servants had gone to bed, for there was no regular nightly watch
in the apartment of the invalid. Mrs. Halliday lay on a sofa in her
husband's room, and Nancy Woolper slept in an adjoining apartment,
always wakeful and ready if help of any kind should be wanted.

The house was very quiet just now. Philip Sheldon walked up and down
the room, thinking; and the creaking of his boots sounded unpleasantly
loud to his ears. He stopped before the fireplace, after having walked
to and fro some time, and began to examine some letters that lay upon
the mantelpiece. They were addressed to Mr. Halliday, and had been
forwarded from Yorkshire. The dentist took them up, one by one, and
deliberately examined them. They were all business letters, and most of
them bore country post-marks. But there was one which had been, in the
first instance, posted from London and this letter Mr. Sheldon examined
with especial attention.

It was a big, official-looking document, and embossed upon the adhesive
envelope appeared the crest and motto of the Alliance Insurance Office.

"I wonder whether that's all square," thought Mr. Sheldon, as he turned
the envelope about in his hands, staring at it absently. "I ought to
make sure of that. The London postmark is nearly three weeks old." He
pondered for some moments, and then went to the cupboard in which he
kept the materials wherewith to replenish or to make a fire. Here he
found a little tin tea-kettle, in which he was in the habit of boiling
water for occasional friendly glasses of grog. He poured some water