“It is paper of native Indian manufacture，” he remarked. “It hasat some time been pinned to a board. The diagram upon it appearsto be a plan of part of a large building with numerous halls，corridors， and passages. At one point is a small cross done in redink， and above it is ‘3.37 from left，’ in faded pencil-writing. In theleft-hand corner is a curious hieroglyphic like four crosses in a linewith their arms touching. Beside it is written， in very rough andcoarse characters， ‘the sign of the four—Jonathan Small， MahometSingh， Abdullah Khan， Dost Akbar.’ No， I confess that I do notsee how this bears upon the matter. Yet it is evidently a documentof importance. It has been kept carefully in a pocketbook， for theone side is as clean as the other.”
“It was in his pocketbook that we found it.”
“Preserve it carefully， then， Miss Morstan， for it may prove tobe of use to us. I begin to suspect that this matter may turn out tobe much deeper and more subtle than I at first supposed. I mustreconsider my ideas.”
He leaned back in the cab， and I could see by his drawn browand his vacant eye that he was thinking intently. Miss Morstanand I chatted in an undertone about our present expeditionand its possible outcome， but our companion maintained hisimpenetrable reserve until the end of our journey.
It was a September evening and not yet seven o’clock， but theday had been a dreary one， and a dense drizzly fog lay low uponthe great city. Mud-colored clouds drooped sadly over the muddystreets. Down the Strand the lamps were but misty splotches ofdiffused light which threw a feeble circular glimmer upon the slimypavement. The yellow glare from the shop-windows streamed outinto the steamy， vaporous air and threw a murky， shifting radianceacross the crowded thoroughfare. There was， to my mind，something eerie and ghostlike in the endless procession of faceswhich flitted across these narrow bars of light—sad faces andglad， haggard and merry. Like all human kind， they flitted fromthe gloom into the light and so back into the gloom once more. Iam not subject to impressions， but the dull， heavy evening， withthe strange business upon which we were engaged， combinedto make me nervous and depressed. I could see from MissMorstan’s manner that she was suffering from the same feeling.
Holmes alone could rise superior to petty influences. He held hisopen note-book upon his knee， and from time to time he jotteddown figures and memoranda in the light of his pocket-lantern.
At the Lyceum Theatre the crowds were already thick at theside-entrances. In front a continuous stream of hansoms andfour-wheelers were rattling up， discharging their cargoes of shirtfrontedmen and beshawled， bediamonded women. We had hardlyreached the third pillar， which was our rendezvous， before a small，dark， brisk man in the dress of a coachman accosted us.
“Are you the parties who come with Miss Morstan？” he asked.
“I am Miss Morstan， and these two gentlemen are my friends，”
said she.
He bent a pair of wonderfully penetrating and questioning eyesupon us.
“You will excuse me， miss，” he said with a certain doggedmanner， “but I was to ask you to give me your word that neither ofyour companions is a police-officer.”
“I give you my word on that，” she answered.
He gave a shrill whistle， on which a street Arab led across afour-wheeler and opened the door. The man who had addressedus mounted to the box， while we took our places inside. We hadhardly done so before the driver whipped up his horse， and weplunged away at a furious pace through the foggy streets.
The situation was a curious one. We were driving to an unknownplace， on an unknown errand. Yet our invitation was either acomplete hoax—which was an inconceivable hypothesis—or elsewe had good reason to think that important issues might hang uponour journey. Miss Morstan’s demeanor was as resolute and collectedas ever. I endeavored to cheer and amuse her by reminiscences ofmy adventures in Afghanistan； but， to tell the truth， I was myselfso excited at our situation and so curious as to our destination thatmy stories were slightly involved. To this day she declares that Itold her one moving anecdote as to how a musket looked into mytent at the dead of night， and how I fired a double-barrelled tigercub at it. At first I had some idea as to the direction in which wewere driving； but soon， what with our pace， the fog， and my ownlimited knowledge of London， I lost my bearings and knew nothingsave that we seemed to be going a very long way. Sherlock Holmeswas never at fault， however， and he muttered the names as the cabrattled through squares and in and out by tortuous by-streets.
“Rochester Row，” said he. “Now Vincent Square. Now we comeout on the Vauxhall Bridge Road. We are making for the Surreyside apparently. Yes， I thought so. Now we are on the bridge. Youcan catch glimpses of the river.”
We did indeed get a fleeting view of a stretch of the Thames，with the lamps shining upon the broad， silent water； but our cabdashed on， and was soon involved in a labyrinth of streets uponthe other side.
“Wordsworth Road，” said my companion. “Priory Road. LarkHall Lane. Stockwell Place. Robert Street. Cold Harbor Lane. Ourquest does not appear to take us to very fashionable regions.”
We had indeed reached a questionable and forbiddingneighborhood. Long lines of dull brick houses were only relievedby the coarse glare and tawdry brilliancy of public houses at thecorner. Then came rows of two-storied villas each with a frontingof miniature garden， and then again interminable lines of newstaring brick buildings—the monster tentacles which the giantcity was throwing out into the country. At last the cab drew upat the third house in a new terrace. None of the other houseswere inhabited， and that at which we stopped was as dark asits neighbors， save for a single glimmer in the kitchen-window.