Many Chicago citizens run towards the wall, and soldiers under Evelyn
are told to shut down the perimeter, and no one is allowed through.
Evelyn directs Jack Kang of Candor to hold trials for the Erudite and
Dauntless conspirators, a number of them becoming executions, starting
with Max. Evelyn and Johanna attempt to pressure Tris and Four into
taking leadership positions in the new coalition, but both refuse. After
seeing that the hostile situation within the city is only going to get
worse, Tris escapes with Four, Caleb, Christina, Tori, and Peter to
journey beyond the wall that encloses Chicago, although Tori is killed
by Edgar in the attempt.
The group is ambushed by Edgar, who is later disabled by an armed
group of individuals and airships. The soldiers take the group to the
Bureau of Genetic Welfare, a highly advanced city where they learn that
years ago, the government believed that society's problems were caused
by "damaged genes". In an attempt to create a better society, they began
to modify people's genes, with disastrous results. The government set
up "experiments" in an attempt to repair this mistake, establishing
isolated cities across the remains of the United States. The hope was to
raise enough genetically pure Divergent individuals to fix the "genetic
damage" left in the wake of the Purity War.
Tris and Four are tested by Matthew and Nita to verify and study
their Divergence. Tris is shown to be truly Divergent, but Four's
genetic structure indicates that his genes are still "damaged". Caleb
and Peter are assigned to surveillance teams that monitor Chicago.
Matthew then brings Tris to the leader of the Bureau, David. David gives
Tris a device that allows her to view her mother's memories, and sees
that her mother was rescued and adopted by the Bureau before
volunteering to join the Chicago experiment out of dedication to the
project. In return for his help in restoring peace to Chicago, Tris
agrees to help David, who claims that only the council he reports to has
the power to intervene.
Meanwhile, Four and Christina train with Nita and joins the Bureau's
military force. They join the military on a rescue mission to a nearby
wasteland village, though Four becomes mistrusting of the Bureau's
intentions after realizing that they were going there to kidnap and
forcefully integrate those children into the Bureau's populace. Upon
their return, Four discreetly petitions Caleb to keep an eye on the
situation in Chicago. Four also attempts to warn Tris of the Bureau's
intentions, but she rejects his ideas.
Caleb warns Four of a rapidly escalating conflict back in Chicago
between Johanna's group of Allegiants and Evelyn's factionless, with
open war becoming an imminent threat. Four appeals to Tris for her to
return to Chicago with him to end the bloodshed, but she decides to go
with David to Providence to meet with the council. David agrees to
reinsert Four back in Chicago, escorted by Matthew and some Bureau
soldiers. Once in the air, Matthew quietly reveals to Four that the
flight is a trap and he is meant to be killed. A skirmish breaks out and
Four defeats all of the soldiers, though the airship crashes as a
result. Matthew gives Four his ID card to get through the cloak wall,
saying that he doesn't believe in David's work anymore and that he wants
to help. Four proceeds to Chicago while Matthew remains behind to be
rescued by the Bureau and warn Tris.
Meanwhile, Tris and David meet with the council. Tris disagrees with
the council's objectives and criticizes how they have done nothing to
stop the violence in Chicago. The council responds that David had the
power to intervene whenever he desired, revealing that he had lied to
her from the beginning. Tris remarks during the return flight to the
Bureau that she never should have trusted him, ending their partnership.
Upon her return, she gathers Caleb and Christina in David's airship to
return to Chicago, and Nita aids them in escaping.
Four is captured by the factionless and confronts Evelyn to end the
violence, though she shows no intention of standing down. Tris, Caleb,
and Christina arrive shortly after to find the city tearing itself apart
at the opening stage of a full assault by the Allegiant. David makes a
deal with Peter in exchange for Peter's promotion and inserts him into
Chicago to convince Evelyn to deploy a hidden Bureau stockpile of gas to
wipe the memories of the attackers and force a peace in her favor, to
which she reluctantly agrees. Peter takes her to a vault where she can
deploy the gas across the city but remain safe herself, making her the
only individual in Chicago who will remember any of those events.
Tris and Christina fight through the factionless and arrive at the
vault, having rescued Four along the way. At the vault door, Four
convinces Evelyn to stop the gas attack, as he wouldn't remember who she
was if she carried it out. She folds and stops the release, and is shot
by a frustrated Peter. Peter gloats in his victory until the same gas
starts releasing inside the vault as well. Realizing David has betrayed
him, Peter opens the vault so Tris and Four can stop the gas release and
flees back towards the cloak wall, as Four says he will find him and
make him pay for badly wounding his mother.
Caleb arrives and aids Tris in destroying the gas dispersion hub,
stopping the release. The main characters gather atop the Erudite
building as they watch the stolen shuttle fly back towards the Bureau,
heavily laden with explosives. Tris transmits a message to the whole
city, revealing to them the existence of the Bureau and that Chicago was
an experiment of the Pure. Her message to the Bureau is that Chicago is
no longer their experiment, but the home of its citizens. Caleb
detonates the explosives at the end of the message, tearing a massive
hole through the cloak wall and revealing the two cities to each other.
The film ends with the Chicago characters gazing at the Bureau in the
distance, with David standing behind Tris, glaring at her.
