"The King Must Die" is a novel by Mary Renault that retells the ancient Greek myth of Theseus. The story follows Theseus as he embarks on a journey from his home in Troizen to Crete, where he must confront the Minotaur, a creature that demands human sacrifices. The narrative explores themes of fate, leadership, and sacrifice. As Theseus navigates the challenges of his destiny, he grapples with the expectations of being a hero and the complexities of power. The novel combines historical elements with myth, providing a rich backdrop for Theseus's transformation and struggles.