March Books 3) The Hound of the Baskervilles, by Arthur Conan Doyle
"Sir Charles lay on his face, his arms out, his fingers dug into the ground, and his features convulsed with some strong emotion to such an extent that I could hardly have sworn to his identity. There was certainly no physical injury of any kind. But one false statement was made by Barrymore at the inquest. He said that there were no traces upon the ground round the body. He did not observe any. But I did--some little distance off, but fresh and clear." "Footprints?" "Footprints." "A man's or a woman's?" Dr. Mortimer looked strangely at us for an instant, and his voice sank almost to a whisper as he answered. "Mr. Holmes, they were the footprints of a gigantic hound!"
And so we are off to Dartmoor, in a tale of ancient legends and tangled family histories of criminality and concealed relationships, in what I think is the best of the Sherlock Holmes stories - Doyle does very well at the atmospheric description, and is getting much better at characterization - Watson getting increasingly irritated by Holmes not letting him know what he is up to. I know the story so well that it is actually quite difficult to judge how well it works as a mystery, but it is very entertaining.