imperfect glimpse of it. It does not await her in front of the house,
for some reason, but just around the corner in the side turning.
Beyond wondering why Mademoiselle Dorian had selected me as her
medical advisor I had detected nothing suspicious in her behaviour up
to the time of which I am about to speak.

"Last night there was a singular development, and to-night matters
came to a head."

Thereupon Stuart related as briefly as possible the mysterious episode
of the cowled man, and finally gave an account of the last visit of
Mlle. Dorian. Inspector Dunbar did not interrupt him, but listened
attentively to the singular story.

"And there," concluded Stuart, "on the blotting-pad, lies the sealed
envelope!"

Dunbar took it up eagerly. A small hole had been burned in one end of
the envelope and much of the surrounding paper was charred. The wax
with which Stuart had sealed it had lain uppermost, and although it
had been partly melted, the mark of his signet-ring was still
discernible upon it. Dunbar stood staring at it.

"In the circumstances, Inspector, I think you would be justified in
opening both envelopes," said Stuart.

"I am inclined to agree. But let me just be clear on one or two
points." He took out the bulging note-book and also a fountain-pen
with which he prepared to make entries. "About this cabman, now. You
didn't by any chance note the number of his cab?"