In The Stacks

David Brown knows a lot of things. He works in the Chestnut Street Public Library as a book runner, and he knows there are two-hundred and thirty-seven concrete sidewalk squares between the front stoop of his apartment house to the front steps of the library, and fifteen steps to the library’s two front doors. He also knows where every single one of the ten-thousand six-hundred and eighty-three library books are located in the back stacks…until one day, when he discovers a book in the stacks he has never seen before…