The valley of fear

Watson rues that there is a secret in the cipher that they will never know. Holmes is quiet, and then says that it relates to a book; he infers that Porlock assumed he’d have it. They deduce it must be the most commonly possessed book—an almanac (there are too many editions of the Bible, Watson’s first guess). They locate the right almanac and the correct pages and words in order to discern that someone named Douglas is in danger, and a house of Birlstone is somehow involved. Before they can parse these words much further than acknowledging the danger for this gentleman named Douglas, Alec MacDonald of Scotland Yard enters; he is a friend of Holmes’s whom the detective had helped a few times in the past, thereby earning the young, intelligent Scotsman’s respect.