What am I reading

I'm reading a book call "Sherlock Holmes and the Sport of Kings" and the author of this story is Sir Arthur Conan Doyle (1859-1930) so far I have read 2 chapter. One day Sherlock Holmes got a message from an Inspector Gregory saying a very famous race horse have disappear and it trainer got killed as well. First Holmes thought that it was an easy case but as he get deeper it is getting harder and harder.