Twins Richelle and Michelle Bach couldn't be more different, and their paths diverge as they embark after graduation. After several years they both come home for Christmas at their father's bequest.. What happens then forever damages their relationship, and Richelle vows never to see or speak to her sister again. In his last days, her father asks her to forgive Michelle-- but it's too late: Michelle is killed in an accident. Working a hospital PICU, Richelle begins to write a book: The Prodigal Daughter. When she meets Justin Ek, a man who harbors his own loss, a secret promise is revealed. -- adapted from jacket