A Study in Scarlet is the first book or story that mentioned Holmes. We discover how Holmes and Watson meet and come to reside at 221B Baker Street.
Inspector Gregson approaches Holmes to help him with a murder that has taken place at night at Number 3, Lauriston Gardens, near Brixton Road, London. The murder is weird, because nothing has been stolen from the dead man. And there are no marks to indicate a fight. To top all of this, the man lies murdered in a house that has been vacant for a long time. And yes..."RACHE" is written with blood on the wall near the man.
Now, obviously there are many questions - tons of questions, of course, taking the mystery deeper and deeper. All the way back to Utah!