What theme is found in the following quotes from Sir Arthur Conan Doyle?
"Holmes was cold and stern and silent. As the gleam of the street-lamps flashed upon his austere features, I saw that his brows were drawn down in thought and his thin lips compressed. I knew not what wild beast we were about to hunt down in the dark jungle of criminal London, but I was well assured, from the bearing of this master huntsman, that the adventure was a most grave one . . ." - The Adventure of the Empty House
??
Difficult decisions ?
Adventure ?
Friendship ?
None of the above ?