1840. Roza, a young novice of the Black Sisters convent of Bruges, is elected to accompany the legendary Flemish priest De Smet to his missionary post in America. With a few fellow sisters she joins the infamous Oregon trail. Caught up in a flash flood, they are rescued by a clan of nomadic Lakota Sioux on their way to winter camp. Life in survival mode on the prairie gives a new sense of purpose to Roza. Awed by the procreative energy of nature, she becomes a mother. But then De Smet reappears to rescue her and bring her back to civilised society. Now she truly has to make a life-changing choice.