Author Sara Gruen gets lost in her books. “I wasn’t able to immerse myself completely with Water for Elephants,” she says of her 2006 best-seller that became a film starring Reese Witherspoon. “The type of circus I was writing about no longer existed.” For her new book, Gruen spent a total of five weeks in the British Isles, researching, absorbing the culture and immersing herself — literally.