The main theme of the book is the exploration of cultural differences and the challenges that arise when people from different cultures come together in an Australian context. Through Michael and Brolga's relationship, the story examines the ways in which cultural barriers can be overcome through love and understanding. The theme of cultural exploration is further emphasized through Michael's investigation of the bones of human historical significance, which offers insights into the origins of the Aborigines. Additionally, the book touches on issues related to health disparities and how they can stem from one's heritage.

Overall, the book explores the complexities of cultural differences and the impact they can have on individuals and their relationships.