» allegiant · plot
After Evelyn forbids anyone from leaving Chicago, she announces that all Erudite members involved in the previous coup attempt are to be put on trial and executed if found guilty. Tris and Four rescue Caleb from execution and try to escape over the wall, along with Tori, Peter and Christina. The group is ambushed by Edgar, who kills Tori, but the group escapes, and pass the wall and are intercepted by soldiers with advanced weaponry who take the group to the Bureau of Genetic Welfare, a city of advanced technology hidden behind a cloaking shield. After undergoing decontamination, they learn that years ago the U.N. believed that society's problems were caused by "damaged genes". In an attempt to create a better society they began to alter people's genes; this eventually led to the Purity Wars and the destruction of most of the planet. To try to reverse the destruction a series of "experiments" were set up in an attempt to repair this mistake, establishing isolated cities across the remains of the world.
Tris and Four are tested by Matthew and Nita to verify and study their Divergence. Tris is shown to be truly Divergent, and the first Chicago Divergent to be 100% genetically pure, but Four's genetic structure indicates that his genes still carry damage. Caleb and Peter are assigned to surveillance teams that remotely monitor Chicago, while Christine and Four are assigned to the military. Matthew then brings Tris to the leader of the Bureau, David (Jeff Daniels). David gives Tris a device that allows her to view her foster mother's memories, and she sees that her mother was rescued from the wastelands as a child before volunteering to join the Chicago experiment out of dedication to the project. In return for his help in restoring peace to Chicago, which David claims only the council has the power to intervene in, Tris agrees to help David continue the experiment.
Meanwhile, Four and Christina train with Nita. They join the military on a rescue mission to a nearby wasteland village, though Four becomes mistrustful of the Bureau's intentions after realizing that they are simply kidnapping children and wiping their memories with amnesia gas. Four also attempts to warn Tris of the Bureau's intentions, but they are interrupted by a video call from David.
Caleb warns Four of a rapidly escalating conflict back in Chicago between Johanna's group of Allegiants and Evelyn's factionless. Four appeals to Tris for her to return to Chicago with him to end the bloodshed, but she decides to go with David. David agrees to reinsert Four back into 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 transport crashes as a result. Matthew gives Four a device to allow passage through the cloaking shield, and 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 has full power to intervene whenever he desires, revealing that he has lied to her from the beginning. During the return flight to the Bureau, Tris ends their partnership. Upon her return, she gathers Caleb and Christina in David's hovercar to return to Chicago. Nita helps them escape, revealing that David's rule is not popular with everyone in the Bureau.
Four is captured by the factionless and confronts Evelyn to end the violence. Tris, Caleb, and Christina arrive to find the city tearing itself apart at the opening stage of a full assault by the Allegiant. Back at the Bureau 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 amnesia gas to wipe the memories of the attackers and force a peace in her favor, to which she agrees. Peter takes her to a hidden vault.
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 would not remember that she was his mother if she carried it out. She capitulates and stops the release, but is shot in the leg by a frustrated Peter. Peter gloats until the same gas starts flooding 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 cloaking shield, as Four says he will find and kill Peter.
Caleb arrives and aids Tris in destroying the gas dispersion hub, stopping the release. The group gathers atop the Erudite building as they watch David's shuttle autopilot back towards the Bureau, heavily laden with explosives. Tris transmits a message to the whole world, revealing to them the existence of the Bureau and that Chicago was an experiment in genetic purity. 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 Bureau. As the group watches, David's image is revealed standing behind Tris via a Bureau remote viewing device.