He opened the door, and stepping out on to the pavement I handed him half a sovereign, which I was holding in readiness.

He touched his cap.  “Thank ye, sir.  Thank ye very much.”  Then, fumbling in his pocket, he produced a rather dirty and crumpled card.  “I don’t rightly know what the game is, Guv’nor,” he went on in a lowered tone, “but if you should ’appen to want to call on me for evidence any time, Martyn’s Garridge, Walham Green, ’ll always find me.  Ye only need to ask for Dick ’Arris.  They all knows me round there.”

I accepted the card, and having assured Mr. Harris that in the event of my needing his testimony I would certainly look him up, I lit my delayed cigarette and started to stroll back towards Parelli’s.  Whoever my original friend and his pal with the eyeglass might be, I was anxious to give them a few minutes’ law before thrusting myself upon their society.  I had known Parelli’s well in the old days, and remembering the numerous looking-glasses which decorated its walls, I thought it probable that I should be able to find some obscure seat, from which I could obtain a view of their table without being too conspicuous myself.  Still, it seemed advisable to give them time to settle down to dinner first, so, stopping at a newspaper shop at the corner, I spun out another minute or two in buying myself a copy of La Vie Parisienne and the latest edition of the Pall Mall.  With these under my arm and a pleasant little tingle of excitement in my heart I walked up to the door of the restaurant, which a uniformed porter immediately swung open.

I found myself in a brightly lit passage, inhabited by a couple of waiters, one of whom came forward to take my hat and stick.  The other pushed back the glass door which led into the restaurant, and then stood there bowing politely and waiting for me to pass.

I stopped for a moment on the threshold, and cast a swift glance round the room.  It was a large, low-ceilinged apartment, broken up by square pillars, but as luck would have it I spotted my two men at the very first attempt.  They were sitting at a table in one of the farther corners, and they seemed to be so interested in each other’s company that neither of them had even looked up at my entrance.

I didn’t wait for them to do it either.  Quickly and unobtrusively I walked to the corner table on the left of the floor, and sat down with my back towards them.  I was facing a large mirror which reflected the other side of the room with admirable clearness.

A waiter handed me the menu, and after I had ordered a light dinner I spread out La Vie Parisienne on the table, and bending over it made a pretence of admiring its drawings.  As a matter of fact I kept my entire attention focused on the looking-glass.

I could only see the back of the man with the scar, but the face of his companion, who was sitting sideways on, was very plainly visible.  It was a striking-looking face, too.  He seemed to be about thirty-five—­a tall, clean-shaven, powerfully built man, with bright blue eyes and a chin like the toe of a boot.  His hair was prematurely grey, and this, together with the monocle that he was wearing, gave him a curious air of distinction.  He looked like a cross between a successful barrister and a retired prize-fighter.