Past and present collide in this heartfelt novel of love and loss from the National Book Award-winning author of A Wrinkle in Time.

After the tragic death of her son and the seeming collapse of her marriage, Charlotte Napier flees to Portugal in the hopes of finding guidance from her mentor: her mother-in-law, Violet. Instead, she finds solace in the letters of Mariana Alcoforado, a seventeenth-century nun.

Charlotte and Mariana's stories may be different in origin, but they share the same inner turmoil. As she reads the letters, Mariana's spiritual journey sheds light on Charlotte's own crisis. Finding inspiration in the nun's struggles with sin, temptation, and faith, Charlotte gains perspective on her own mind-and sets out to accept the demanding, challenging nature of love.