If you were in a Manhattan hotel 25 years ago, or a German castle recently, you may have heard Robin Meloy Goldsby tinkling the ivories, and not even known it. Her latest book, Piano Girl Playbook: Notes on a Musical Life, captures what it's like to play for all kinds of people in all kinds of places, and still find music at the heart of things. We talk about her storied life (played at Buckingham Palace? Check! Played for naked folks while wearing a concert gown? Done that!), the intentions of the composer, Mr. Rogers, and putting the work in.