On Hiding Things From The Reader

I took up reading "the Adventures of Sherlock Holmes" via the Kindle App because I haven't read very many of them.  Overall, the experience has been fun so far.  I expected some dated language and whatnot, considering its status as a classic, but what I've really noticed is the difference in storytelling.

Some of it just plain wouldn't fly today.

The biggest thing that jumped out at me was one case of hiding stuff from the reader–blatantly.

Spoilers ahead.

During "The Red-Headed League," the...