This is the one where Watson meets Mary and we meet depressed and addict Holmes. Said like that it doesn't sound too interesting but it is. In this second adventure, Holmes is on the trail of a murderer, a thief and a lost treasure, we get a hot pursuit on the Thames and a chase with a dog that ends where it should logically end. This is the story where the famous : "when you have eliminated the impossible, whatever remains, however improbable, must be the truth". If only for that it's worth reading.