"Allegiant" is the third book in the Divergent series written by Veronica Roth. It follows the story of Tris Prior and Tobias Eaton as they navigate a dystopian society divided into factions. The narrative explores themes of loyalty, sacrifice, and the struggle for identity in a world filled with conflict. The book is told from alternating perspectives, providing insight into both Tris and Tobias's thoughts and feelings. As they uncover secrets about their society and face new challenges, they must decide what they are willing to fight for and whom they can trust in their quest for freedom.