h. There, sitting together
in the twilight, I told Holmes of my conversation with the lady. So
interested was he that I had to repeat some of it twice before he was
satisfied.

"This is most important," said he when I had concluded. "It fills up a
gap which I had been unable to bridge in this most complex affair. You
are aware, perhaps, that a close intimacy exists between this lady and
the man Stapleton?"

"I did not know of a close intimacy."

"There can be no doubt about the matter. They meet, they write, there
is a complete understanding between them. Now, this puts a very powerful
weapon into our hands. If I could only use it to detach his wife--"

"His wife?"

"I am giving you some information now, in return for all that you have
given me. The lady who has passed here as Miss Stapleton is in reality
his wife."

"Good heavens, Holmes! Are you sure of what you say? How could he have
permitted Sir Henry to fall in love with her?"

"Sir Henry's falling in love could do no harm to anyone except Sir
Henry. He took particular care that Sir Henry did not make love to her,
as you have yourself observed. I repeat that the lady is his wife and
not his sister."

"But why this elaborate deception?"

"Because he foresaw that she would be very much more useful to him in
the character of a free woman."

All my unspoken instincts, my vague suspicions, suddenly took shape and
centred upon the naturalist. In that impassive colourless man, with his
straw hat and his butterfly-net, I seemed to see something terrible--a
creature of infinite patience and craft, with a smiling face and a
murderous heart.

"It is he, then, who is our enemy--it is he who dogged us in London?"

"So I read the riddle."

"And the warning--it must have come from her!"

"Exactly."

The shape of some monstrous villainy, half seen, half guessed, loomed
through the darkness which had girt me so long.

"But are you sure of this, Holmes? How do you know that the woman is his
wife?"

"Because he so far forgot himself as to tell you a true piece of
autobiography upon the occasion when he first met you, and I dare say
he has many a time regretted it since. He was once a schoolmaster in
the north of England. Now, there is no one more easy to trace than a
schoolmaster. There are scholastic agencies by which one may identify
any man who has been in the profession. A little investigation showed me
that a school had come to grief under atrocious circ