I walked into Murder by the Book on Wednesday knowing one author. I left knowing two. I’ve enjoyed Tom Straw’s writing before I knew who Tom Straw was. Back in the fall of 2009, the second season of “Castle” premiered on our TV screens, but HEAT WAVE, the first book “written by” Richard Castle, showed up on bookshelves. What was this meta magic? Nearly every fall after 2009, when a new Castle season started there was a Castle book. What made the books great was this: unlike the TV show characters Castle and Beckett, their counterparts, Jameson Rook and Nikki Heat, actually got together. It was the mirror universe of…