Pen, Will, and Cat met at college and struck up a remarkable friendship that sustained and shaped them for years, until it ended abruptly, and they went their separate ways. Now, six years later, Pen is a single mother of a five-year-old girl, living with her older brother in Philadelphia and trying to make peace with the sudden death of her father. She decides to accept Cat's invitation to go to their college reunion. What happens there sends them on a journey that changes everything.