I am in Mansion's Catacomb and at the point to finding where the vampire went and I have clicked on everything and I see footprints go under the shelves but can't get it to open
pixel_player98273209
Keep digging past the bookshelf. You will reach another room that shows you how to arrange the books in the shelf, so that a secret passage opens. You can also check the maps and videos in the Wiki: https://diggysadventure.fandom.com/wiki/Halloween_2020