In a dystopian future society, the city of Chicago has been divided into five factions based on human virtues to maintain peace after war: Abnegation (selflessness), Amity (peace), Candor (truth), Dauntless (courage), and Erudite (intelligence). At the age of 16, every individual must take a test that recommends the faction best suited to their personality, but they are then allowed to choose any faction as their permanent group at the Choosing Ceremony. When Beatrice Prior, a member of the Abnegation faction, takes the test, she discovers she is Divergent, meaning she does not fit neatly into any one faction. Her test proctor warns her to keep this a secret, as being Divergent is seen as a threat to the strictly structured society.

Despite her Abnegation roots, Beatrice feels a pull towards the Dauntless faction and ultimately chooses to join them, adopting the name Tris. As she embarks on the grueling initiation process, she struggles to fit in, hiding her secret while trying to understand what being Divergent means for her future. Tris makes both friends and enemies in her new faction and comes to realize that the society she lives in is more fragile and corrupt than she'd been led to believe. Her divergence grants her unique abilities that place her, and anyone she becomes close to, in great danger as political unrest grows within the city walls.