“One more question, and then I have done.  Did you happen to notice that night, or before he left next day, whether he had hurt his left hand?”

“It’s strange that you should speak of that,” said the manager.  “He had cut his left hand rather badly with a broken glass, so he told us.  We gave him some sticking-plaster to do it up with.”

“That will do beautifully,” I said.  “And now perhaps you will add to the kindness you have already done me by letting me see the gentleman in question.  I don’t want to speak to him, but I want to impress his countenance upon my mind.”

“Why not go into lunch?” the manager inquired.  “You will then be able to study him to your heart’s content, without his being any the wiser.  You’re not in uniform, and no one would take you for a detective.”

“An excellent idea,” I replied.  “By the way, while I am upon the subject, I suppose I can rely upon your saying nothing about the matter to him, or to any one else?”

“You may depend upon me implicitly,” he answered.  “I should be scarcely likely to do so, for my own sake.  I trust the matter is not a very serious one.  I should not like to have any scandal in the hotel.”

“Well, between ourselves,” I observed, “I am afraid it is rather a serious affair.  But you may be sure I will do all I can to prevent your name or the hotel’s being mixed up in it.”

Then, as he had proposed, I followed him into the dining-room and took my place at a small table near the window.  At that adjoining me, a tall, swarthy individual, with close-cropped hair, an Italian without doubt, was seated.  He glanced at me as I took my place, and then continued his meal as if he were unaware of my presence in the room.

By the time I had finished my lunch I had thoroughly impressed his face and personality upon my memory, and felt sure that, if necessary, I should know him anywhere again.  My labours, however, were by no means over; in fact they were only just beginning.  What I had against him so far would scarcely be sufficient to justify our applying for a warrant for his arrest.  If I wanted to bring the crime home to him, it would be necessary for me to connect him with it more closely than I had yet done.  But how to do this in the short space of time that was at my disposal I could not see.  The murderer, as I have already said, was no ordinary one, and had laid his plans with the greatest care.  He had taken away the knife, and in all probability had got rid of it long since.  No one had seen him enter the house on the night in question, nor had any one seen him leave it again.  I was nearly beside myself with vexation.  To be so near my goal, and yet not be able to reach it, was provoking beyond endurance.  But my lucky star was still in the ascendant, and good fortune was to favour me after all.