Colleen McCullough's novel 'The Thorn Birds' is set in Australia. It tells the story of the Cleary family on their sheep farm in the Australian outback, and focuses on the forbidden love between the family's beautiful daughter, Meggie, and the parish priest, Father Ralph de Bricassart. The novel spans several decades and explores themes of love, family, ambition, and sacrifice. It became a bestseller and was adapted into a popular television series in 1983.