I watched him with considerable interest.  If he was another of McMurtrie’s mysterious circle, I certainly preferred him to any of the ones I had previously come across.  His face, though strong and hard, had none of Savaroff’s brutality in it, and he was quite lacking in that air of sinister malevolence that seemed to hang about the doctor.

As far as I could see, most of the talking was being done by the man with the scar.  He also appeared to be the host, for I saw him pick up the wine list, and after consulting his companion’s taste give a carefully selected order to the waiter.  Then my own dinner began to arrive, and putting aside La Vie, I propped up the Pall Mall in front of me and started to attack the soup.

All through the meal I divided my attention between the paper and the looking-glass.  I was careful how I made use of the latter, for the waiter was hovering about most of the time, and I didn’t want him to think that I was spying on some of the other customers.  So quite genuinely I waded through the news, keeping on glancing in the mirror over the top of the paper from time to time just to see how things were progressing behind me.

That my two friends were getting along together very well was evident not only from their faces but from the sounds of laughter which at intervals came floating down the room.  Indeed, so animated was their conversation, that although I had begun my dinner later, I had finished some little time before they had.  I had no intention of leaving first, however, so ordering myself some coffee, I sat back in my chair, and with the aid of a cigar, continued my study of the Pall Mall.

I was in the middle of a spirited article on the German trouble, headed “What Does the Kaiser Mean?” when glancing in the mirror I saw a waiter advance to the table behind me, carrying a bottle of port in a basket, with a care that suggested some exceptional vintage.  He poured out a couple of glasses, and then placing it reverently on the table, withdrew from the scene.

I watched both men take a sip, and saw them set down their glasses with a thoroughly satisfied air.  Then the man with the scar made a sudden remark to the other, who, turning his head, looked away over his shoulder into the restaurant.  His attention could only have been withdrawn from the table for a couple of seconds at the most, but in that fraction of time something happened which set my heart beating rapidly in a kind of cold and tense excitement.

So swiftly, that if I had not been looking straight in the mirror I should have missed seeing it, the man with the scar brought his hand down over his companion’s glass.  Unless my eyes were playing me a trick, I distinctly saw him empty something into the wine.

There are rare occasions in life when one acts instinctively in the right way before one’s mind has had time to reason matters out.  It was so with me now.  Without stopping to think, I whipped out a pencil from my pocket, and snatched away a piece of white paper from underneath the small dish of candied fruit in front of me.  Spreading it out on the table I hastily scribbled the following words: