Anyway, Hound is Sherlock book #5, first serialised in the Strand magazine before being published as a stand-alone novel. It is the third of the four novels, but comes after an eight year gap since the previous the short story collection The Memoirs. It was published (supposedly to quell the public appetite for more Holmes and Watson) despite the fact that in the last story of The Memoirs (The Final Problem) Holmes gets into a bit of a tussle with his arch enemy Moriaty at the Reichenbach Falls, and appears to fall to his death. However, ACD sidesteps that problem by setting the events of The Hound at an earlier date! Readers had to wait a further three years for the The Return of Sherlock Holmes to find out what had happened.
As for Hound itself, most definitely not my favourite. Holmes himself is absent from the entire middle section of the novel, and the culprit comes as little surprise. On reflection would probably have worked better as on of the short stories.
As it happens, of my many book series I have been attempting to read over the years, Holmes was one of them, and I was up to #4 previously, so I can enjoy getting back to some short stories now - much more fun.