The story begins three days after the assault on the Abnegation faction by Erudite leader Jeanine’s mind-controlled Dauntless soldiers. Dauntless leader Eric and his platoon search through the wreckage of Abnegation for a box of unknown origin that contains the symbols for each faction. They recover the box and take it to Erudite. Jeanine claims it contains data from the city’s founders and the means to end the Divergence problem–the issue of individuals having the qualities of multiple factions. Only a Divergent can open the box, so she orders all Divergents hunted down and captured. Tris, Four, Peter, and Caleb hide within the Amity compound. Soon after, Eric and his fleet arrive to test all the occupants for Divergence. Peter gives up the group’s location as Tris, Four, and Caleb escape and board a train headed into Factionless territory. A fight ensues with the Factionless aboard the train. Four reveals his true name, Tobias Eaton, to the Factionless, who reply that they have been searching for him. Four, Tris and Caleb are given safe passage into the heart of Factionless. There, Tris and Caleb discover that Factionless’ leader is Four’s mother, Evelyn Johnson-Eaton. Evelyn suggests that Dauntless and Factionless should join their forces against Erudite. The next morning, the three leave Factionless for Candor to meet up with the remaining Dauntless. During the trek, Caleb tells Tris that he cannot continue with them and goes in a different direction.
劇情承接上集《分歧者》震撼結局，翠絲（雪琳·伍德莉）與四號（席歐·詹姆斯）搗毀舊世界的秩序，曝露他們的分歧者身分之後，如今已淪為逃犯，被博學派領導人珍寧（凱特·溫絲蕾）佈下天羅地網追捕！ 大權在握並掌控無畏派叛軍的珍寧，在已成為反烏托邦本營的芝加哥廢墟中，大肆搜索所有潛在的分歧者。翠絲與四號兩人暗中遊走於友好派、直言派、克己派、無畏派等派別，企圖尋找同盟。親友因她牽連而喪命的悲痛，令翠絲必須勇敢拋開內疚，重親定義自己，找出她家人不借犧牲生命所要保護的信念，和博學派不擇手段對她趕盡殺絕的原因。翠絲決定面對自己最深沉黑暗的恐懼，接受一連串近乎不可能的挑戰，才能揭開這個世界過去的祕密，以及未來的真相。