In a future post apocalyptic Chicago, society has been divided into five factions: Abnegation, Amity, Candor, Dauntless, and Erudite. The remaining population, called the Factionless, have no status or privilege. Upon turning sixteen, children undergo a serum-induced psychological aptitude test, which informs them of their best-suited faction, but can choose any as their permanent group at the subsequent Choosing Ceremony.
Sixteen-year-old Beatrice Prior was born and raised into Abnegation, which runs the government. Her father, Andrew, serves on the ruling council along with Abnegation's leader, Marcus Eaton. After her test results show equal attributes of multiple factions- Abnegation, Erudite, and Dauntless- making her Divergent, her proctor Tori Wu, a Dauntless woman, records her results as Abnegation. She warns her to conceal her true results; as Divergents can think independently and sense any serums injected into them, the government feels they threaten the existing social order.
The next day, at the Choosing Ceremony, Beatrice's brother Caleb chooses Erudite, while, after some hesitation, she chooses Dauntless. Afterwards, she meets Christina, Al, and Will, three other faction transfers to Dauntless. Christina and Al are from Candor, and Will is from Erudite.
Eric Coulter, a brutal Dauntless leader, reminds the initiates that anyone not meeting the faction's high expectations of commitment and fearlessness will become Factionless. Beatrice volunteers to jump from a tall building into a dark hole and lands into a net. When Four, a transfer initiates' instructor, asks her name, she shortens it to "Tris", shedding her earlier identity.
Tris initially struggles in Dauntless training and ranks far below the cutoff after the first evaluation, but with Four's help, she slowly improves. Eric matches her against her nemesis, Candor transfer Peter Hayes, in a fight, which ends with Tris' defeat and recovery in the infirmary.
Unwilling to miss the most important test, Capture The Flag, she leaves the infirmary, joins the other initiates, secures her team's victory, and makes the final cut. In the next phase of training, the initiates face their worst fears in psychological simulations. Tris's divergence allows her to creatively solve the tests, but Four warns her to hide her abilities and solve them as a normal Dauntless would.
Tris visits Caleb, who tells her that Erudite plans to overthrow Abnegation. When she returns, Al, Peter, and their fellow Candor transfer Drew attack her, but Four rescues her. The next day, Al begs Tris to forgive him but she refuses and calls him a coward. He later kills himself by jumping into "The Pit", rather than live with the shame.
To prepare her for the final test, Four takes Tris into his own fear simulations, where she learns he is Tobias Eaton, and his father Marcus used to beat him as a child. Tris then passes her test and officially joins Dauntless. The Dauntless recruits are injected with a serum from Erudite, supposedly for tracking but actually for mind control.
The next morning, the Dauntless prepare to execute Abnegation under Erudite's orders. As the serum fails on Divergents, Tris must blend in to avoid suspicion. She finds Four, who reveals himself to also be Divergent. When the Dauntless move to raid Abnegation, they separate from the group and attempt to locate Tris's parents. However, Eric realizes Four is not under control so captures both of them, taking Four into custody and ordering Tris's execution. Her mother Natalie appears and saves her but is shot and killed as they attempt to escape.
Tris finds her father hiding with Caleb, Marcus, and several Abnegation members. The group sneaks into Dauntless headquarters, where Tris encounters Peter and forces him to lead them to Erudite's control center. Her father sacrifices himself in a shootout, so Tris goes in alone to find Four, who is now under stronger mind control designed for Divergents.
Knowing Four's fears, Tris manages to wake him from the mind control, and both enter the central control room, where Erudite's leader Jeanine Matthews has Dauntless execute nearly the entire Abnegation faction. Tris uses a sample of the mind control serum on her to force her to cancel the program. The group escapes the compound and boards a train out of the complex.
