When Erin Connolly accidentally donates her favorite book to a little community library, she's devastated. But then the book turns up a week later with fresh notes in the margins, along with an invitation in a copy of Great Expectations to meet her new pen pal. A life-changing conversation, written only in the margins of classic books, begins between Erin and her Mystery Man. As the book exchange continues, they begin falling into a friendship ... and maybe something more. But Erin and her pen pal have a shared history neither of them has guessed. Faced with painful reminders of the past, Erin finds herself at a crossroads. One that could change her life forever.