Set in northern Spain in 1250 AD, the book tells the story of a Basque girl on the brink of adulthood and her quest to find a new life. She watches in horror as her mother is accused of witchcraft and burned at the stake. She knows the angry mob is coming for her next. She is forced to run from the only life she has known, into a frightening future.
After her mother's torture and death Amika flees into the forest. At first, she is completely alone. She ekes out a living foraging for plants she recognizes from her mother's garden. An old woman, Ane, a devotee of the regional pre-christian tradition, rescues her and teaches her the "old ways" until they too are hunted down and jailed. Amika escapes but Ane does not.
Before Amika escapes Ane gives her an amulet to place at the foot of the Cruz de Ferro, the Iron Cross, a holy site along the Camino de Santiago. A sympathetic priest who remembers Amika's mother as a healer enables Amika to escape. As the price for her freedom, he gives her four amber stones, and the mission to find four lessons along the Way of Saint James to prove there is a benevolent God. Then she must deposit the stones at the foot of the Iron Cross and give thanks.
Amika undertakes a "hero's journey" to fulfill the mission both Ane and the priest have given her. The journey takes place along the Camino de Santiago, an 800-year-old pilgrimage route across northern Spain. She meets many fellow pilgrims and forms a deep relationship with a man and young girl. After are separated along the way Amika must begin a new life, pining for the man and the girl. In the end they are reunited and begin their life together.