nnect him with the river tragedy; or
rather to show that he had communicated with the unfortunate Mrs.
Courtenay.

In company we walked to Leman Street Police Station, one of the chief
centres of the Metropolitan Police in the East End, and there, in an
upper office, Ambler had a long consultation with the sergeant of the
Criminal Investigation Department.

I described the appearance of the body, and stated my suspicions of
poisoning, all of which the detective carefully noted before going
forth to make his own examination. My address was taken, so that I
might assist at the post-mortem, and then, shortly after midnight I
drove back westward through the City with Ambler at my side.

He spoke little, and when in Oxford Street, just at the corner of
Newman Street, he descended, wished me a hurried good-night, and
disappeared into the darkness. He was often given to strange vagaries
of erratic movement. It was as though some thought had suddenly
occurred to him, and he acted at once upon it.

That night I scarcely closed my eyes. My brain was awhirl with
thoughts of all the curious events of the past few months--the
inexplicable presence of old Mr. Courtenay, and the subsequent death
of Mary and of the only man who, according to Ambler, knew the
remarkable secret.

Ethelwynn's strange words worried me. What could she mean? What did
she know? Surely hers could not be a guilty conscience. Yet, in her
words and actions I had detected that cowardice which a heavy
conscience always engenders. One by one I dissected and analysed the
Seven Secrets, but not in one single instance could I obtain a gleam
of the truth.

While at the hospital next day I was served with a notice to assist at
the post-mortem of the unfortunate Lane, whose body was lying in the
Shadwell mortuary; and that same afternoon I met by appointment Doctor
Tatham, of the London Hospital, who, as is well known, is an expert
toxicologist.

To describe in technical detail the examination we made would not
interest the general reader of this strange narrative. The average man
or woman knows nothing or cares less for the duodenum or the pylorus;
therefore it is not my intention to go into long and wearying detail.
Suffice it to say that we preserved certain portions of the body for
subsequent examination, and together were engaged the whole evening in
the laboratory of the hospital. Tatham was well skilled in the minutiae
of the tests. The exact determinatio