Orphan Train has two parallel stories. In one, Niamh, an Irish immigrant girl in Depression era New York City, finds herself an orphan after a devastating fire. She is put on an orphan train, a charitable organization's attempt to remove orphan children from the streets of the city by taking them out west on a train. The second story is about Molly, a young girl whose father has died and whose mother is in jail. She is in the modern era foster-care system in Bar Harbor, Maine.
These two stories converge in a fascinating and satisfying way. I couldn't put this book down. As I said, the book is really written for an adult audience, but a mature young adult reader who enjoys historical fiction and family relationships would probably enjoy this book.