“For you to know could not have helped us， and might possiblyhave led to my discovery. You would have wished to tell mesomething， or in your kindness you would have brought me outsome comfort or other， and so an unnecessary risk would be run.
I brought Cartwright down with me—you remember the littlechap at the express office—and he has seen after my simple wants：
a loaf of bread and a clean collar. What does man want more？ Hehas given me an extra pair of eyes upon a very active pair of feet，and both have been invaluable.”
“Then my reports have all been wasted！"—My voice trembledas I recalled the pains and the pride with which I had composedthem.
Holmes took a bundle of papers from his pocket.
“Here are your reports， my dear fellow， and very well thumbed，I assure you. I made excellent arrangements， and they are onlydelayed one day upon their way. I must compliment you exceedinglyupon the zeal and the intelligence which you have shown over anextraordinarily difficult case.”
I was still rather raw over the deception which had beenpractised upon me， but the warmth of Holmes’s praise drove myanger from my mind. I felt also in my heart that he was right inwhat he said and that it was really best for our purpose that Ishould not have known that he was upon the moor.
“That’s better，” said he， seeing the shadow rise from my face.
“And now tell me the result of your visit to Mrs. Laura Lyons—itwas not difficult for me to guess that it was to see her that you hadgone， for I am already aware that she is the one person in CoombeTracey who might be of service to us in the matter. In fact， if youhad not gone to-day it is exceedingly probable that I should havegone to-morrow.”
The sun had set and dusk was settling over the moor. The airhad turned chill and we withdrew into the hut for warmth. There，sitting together in the twilight， I told Holmes of my conversationwith the lady. So interested was he that I had to repeat some of ittwice before he was satisfied.
“This is most important，” said he when I had concluded. “It fillsup a gap which I had been unable to bridge， in this most complexaffair. You are aware， perhaps， that a close intimacy exists betweenthis lady and the man Stapleton？”
“I did not know of a close intimacy.”
“There can be no doubt about the matter. They meet， theywrite， there is a complete understanding between them. Now， thisputs a very powerful weapon into our hands. If I could only use itto detach his wife——”
“His wife？”
“I am giving you some information now， in return for all that youhave given me. The lady who has passed here as Miss Stapleton isin reality his wife.”
“Good heavens， Holmes！ Are you sure of what you say？ Howcould he have permitted Sir Henry to fall in love with her？”
“Sir Henry’s falling in love could do no harm to anyone exceptSir Henry. He took particular care that Sir Henry did not makelove to her， as you have yourself observed. I repeat that the lady ishis wife and not his sister.”
“But why this elaborate deception？”
“Because he foresaw that she would be very much more usefulto him in the character of a free woman.”
All my unspoken instincts， my vague suspicions， suddenlytook shape and centred upon the naturalist. In that impassive，colourless man， with his straw hat and his butterfly-net， I seemedto see something terrible—a creature of infinite patience andcraft， with a smiling face and a murderous heart.
“It is he， then， who is our enemy—it is he who dogged us inLondon？”
“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 thewoman is his wife？”
“Because he so far forgot himself as to tell you a true piece ofautobiography upon the occasion when he first met you， and Idare say he has many a time regretted it since. He was once aschoolmaster in the north of England. Now， there is no one moreeasy to trace than a schoolmaster. There are scholastic agencies bywhich one may identify any man who has been in the profession.
A little investigation showed me that a school had come to griefunder atrocious circumstances， and that the man who had ownedit—the name was different—had disappeared with his wife. Thedescriptions agreed. When I learned that the missing man wasdevoted to entomology the identification was complete.”
The darkness was rising， but much was still hidden by theshadows.
“If this woman is in truth his wife， where does Mrs. Laura Lyonscome in？” I asked.
“That is one of the points upon which your own researches haveshed a light. Your interview with the lady has cleared the situationvery much. I did not know about a projected divorce betweenherself and her husband. In that case， regarding Stapleton as anunmarried man， she counted no doubt upon becoming his wife.”
“And when she is undeceived？”
“Why， then we may find the lady of service. It must be our firstduty to see her—both of us—to-morrow. Don’t you think， Watson，that you are away from your charge rather long？ Your place shouldbe at Baskerville Hall.”
The last red streaks had faded away in the west and night hadsettled upon the moor. A few faint stars were gleaming in a violetsky.
“One last question， Holmes，” I said， as I rose. “Surely there is noneed of secrecy between you and me. What is the meaning of itall？ What is he after？”
Holmes’s voice sank as he answered： ——
“It is murder， Watson—refined， cold-blooded， deliberatemurder. Do not ask me for particulars. My nets are closing uponhim， even as his are upon Sir Henry， and with your help he isalready almost at my mercy. There is but one danger which canthreaten us. It is that he should strike before we are ready to doso. Another day—two at the most—and I have my case complete，but until then guard your charge as closely as ever a fond motherwatched her ailing child. Your mission to-day has justified itself，and yet I could almost wish that you had not left his side. Hark！”