The Great Hunt (#1, The Hunt Series)
by Kachi Ugo
Having just turned seventeen, Samantha Krus must embark on a once in a five year pilgrimage of blood to Aloehexa called the Great Hunt. But Sam, in a fit of compassionate rage, has broken the most sacred law known to Hannibus. However, when she discovers a plot to wipe out Aloehexans in the capital city of Granadia with a chemical weapon, she risks everything to stop it.