After spending 7 years on Devil's Island, a French penal colony off the coast of French Guiana, Valyon, a once-great Paris surgeon, is transferred to the prison city of Cayenne, where he is permitted to marry Jeanette, his faithful mistress, and to cultivate a small piece of land. They become the parents of a son, Léon, who, grown to manhood, also becomes a surgeon. After the death of his father, Léon arranges for his mother to be released from Cayenne.