In the fall of 1957, Olivia McAlister is living in Opelika, Mississippi, caring for her two girls, Grace and June, and her husband. She dreams of living a much larger life--seeing Paris and returning to her wartime job at a landing boat factory in New Orleans. As she watches over the birds in her yard, Olivia feels like an "accidental"--a migratory bird blown off course.When Olivia becomes pregnant again, she makes a fateful decision that reverberates throughout Grace's and June's lives. Grace, caught up in an unconventional love affair, becomes one of the "girls who went away" to have a baby in secret. June, guilt-ridden for her part in exposing Grace's pregnancy, eventually makes an unhappy marriage. Meanwhile Ed Mae Johnson, an African American care worker in a New Orleans orphanage, is drastically impacted by Grace's choices.As the years go by, their lives intersect in ways that reflect the unpredictable flights of birds diverted from their expected journey--and the consolations of imperfect return.