The Sign of Four*: (By Sir Arthur Conan Doyle). This is the second Sherlock Holmes story. Though it was the second one written by Doyle it is written as if many years have already gone by and Holmes and Watson have had a plethora of adventure together. It reads just as well as A Study in Scarlet and likewise doesn't really feel that old.
Also like A Study in Scarlet** there's a section in which Doyle takes time to explain the entire back story of the villain. Though unlike A Study in Scarlet, he lets you know that is what he's going to do ahead of time so there's no literary whiplash as you try to figure out what happened. Also this flash back is much shorter.
Story wise, the book definitely has a more polished feel and consequently it's a better book.
I suppose it's probably telling of me that the thing I'll probably remember most about the book is this little exchange between Watson and Mr. Sherman, the owner of a house that he is trying to wake up and get a hound dog from in the middle of the night.
"Go on!" yelled the voice. "So help me gracious, I have a wiper in this bag, and I'll drop it on your 'ead if you don't hook it!"
"But I want a dog," I cried.
"I won't be argued with!" shouted Mr. Sherman. "Now stand clear, for when I say 'three,' down goes the wiper."
The Sign of Four: A
* - Also often called The Sign of the Four
** - I was going to start abbreviating A Study in Scarlet by the first letters of the capitalized words but then thought better of it.