I don't know whether I really enjoyed this book this much or because I read it in four hours I can't really remember any of the bad parts, but this book was definitely my favourite of the series.
This book had everything I ever wanted from America, she started actually telling people her ideas, which most of the time were pretty good, she worked out her feelings and expressed them (even if it was at the end), and she helped organise a rebellion. Reading this book it was like there never was a love triangle, there was no America being a wuss and not saying anything to Aspen and letting him pursue her, there was no angst over who she should be with, it was just pretty much a love story between her and Maxon, which I have no problem with. Also I feel like this book is probably the only one in the series that passes the Bechdel test, I loved that Celeste got some reasoning for her behaviour and that she and the other girls all became quite good friends, not even needing to talk about Maxon (for once). My favourite character in this book was probably Celeste, everyone else had a point in this book where they made me really dislike them, and ironically Celeste was probably the only one who didn't do that, I wasn't expecting the depth that she got in this book but I am really grateful for it. I would definitely recommend finishing this series, even if, like me, you didn't enjoy The Elite that much.
America and Maxon are summoned by the Northern rebels in the middle of the night because they want to show their support of Maxon and tell him they'll help fight against the Southern rebels if he gives them a sign that he's willing to change and get rid of the castes once he's in power. She and Georgia, one of the northern rebels become fast friends and Maxon has an ally in August, the other rebel who came. The Southern rebels start increasing their attacks to try to force them to stop the Selection, so America and Maxon get Aspen help them sneak out and meet with August and Georgia in the middle of the night. They learn that they need weapons if they are to go against the Southern rebels, so America invites both Georgia and Nicoletta, the princess of Italy, to one of the events the elite have to participate in and gets Italy to fund the Northern rebels weapons so they can help prevent the attacks. Maxon shows America his room, at this point both know they love the other, but neither is willing to admit it unless the other does first, and they are about to have sex when a guard shows up looking for America because her dad has died. America returns home for the funeral and learns that her dad was a member of the northern rebels and the way you identify them is by the star of david they display, usually as part of their wardrobe. She returns to the palace and finds all the girls from the selection are back because Maxon has narrowed it down Kriss and America and is announcing his engagement the next day. She goes to her room and Maxon comes to visit to give her an envelope full of letters he wrote while she was away and to tell her that she's the one he's picking. They spend the night together and when Aspen walks in on them in the morning Maxon goes to leave and while America is assuring Aspen that they didn't have sex Maxon comes back and sees them together. Although America assures him that she loves him and she and Aspen are just friends, Maxon rejects her and tells her she'll leave tomorrow. The next day at the engagement announcement, the Southern rebels suddenly attack having been scattered throughout the castle, when one comes to shoot Maxon, he instead decides to make him suffer and shoot America, Maxon jumps in front of her and takes the bullet. Aspen kills the shooter and Maxon tells him to take America to safety before helping him. When America is let out of her safe room after the battle she learns Maxon is alive and is King because his mother and father were both killed and when she goes to his room he shows her the documents he's making that will get rid of caste eight by absorbing it into caste seven, he then needs to work on it more but he will slowly get rid of the caste system. He proposes to her and she says yes. The book ends with America walking down the aisle at her wedding to Maxon and him saying "hello my dear" and she replies with "oh don't start" (and then I cried).