BAR HARBOR — Twenty-five years ago, a young ranger at Acadia National Park closed the Nature Center at Sieur de Monts Spring, grabbed her lunch and a book, and made her way to the Tarn where she settled herself beside the water to read.

But this wasn’t just any old book. It was her author’s copy of “Green Rider,” the first book in what would become a New York Times bestselling fantasy series. She’d had her copies delivered to her office at the park but hadn’t had time to look at one until her lunch break.