The Valley of Fear is the fourth and final Sherlock Holmes novel by Sir Arthur Conan Doyle. It is loosely based on the Molly Maguires and Pinkerton agent James McParland. The story was first published in the Strand Magazine between September 1914 and May 1915. (Wikipedia)
If his emotions were dulled, his intellectual perceptions were exceedingly active. There was no trace then of the horror which I had myself felt at this curt declaration; but his face showed rather the quiet and interested composure of the chemist who sees the crystals falling into position from his oversaturated solution.
“Remarkable!” said he. “Remarkable!”
“You don’t seem surprised.”
“Interested, Mr. Mac, but hardly surprised. Why should I be surprised? I receive an anonymous communication from a quarter which I know to be important, warning me that danger threatens a certain person. Within an hour I learn that this danger has actually materialized and that the person is dead. I am interested; but, as you observe, I am not surprised.”