The following version of this book was used to create this study guide: Cass, Kiera. The One. Harper Collins, 2014. Kindle Edition.

As the third installment of the Selection series begins – told from the first-person perspective of America Singer - America has decided that she wants to win Maxon’s hand and end the Selection. In an attempt to do so, she tries to seduce him. This approach does not work, however, as both of them know this is not who she is.

During this same period, rebels continue to attack the palace. One day, two Northern rebels come to talk to America and Maxon. One is August Illea who, under normal circumstances. would have inherited the throne. The other is his fiancée, Georgia, whom America met in the previous installment of the series. August does not want the throne as Maxon fears. Instead, among other things, he wants Maxon to end the caste system and to marry America. Maxon does not commit to marrying America, but is quiet as August talks about ending the caste system. Through Georgia, America learns that they are rooting for her and one other girl.

The Southern rebels begin to become more forceful and vow that if the Selection does not end, they will start killing people starting with twos and moving down to the lower castes. The king informs the people of this during a broadcast and tells them to stay close to home and secure themselves. The other girls say something similar, but America tells the people to fight. During a secret meeting she and Maxon have with August and Georgia to find out how many people have died, August and Georgia credit her with saving lives. During the same meeting, they say that it would help if they had arms. America figures out a way to get weapons for them and works with Maxon to be able to do so.

America’s popularity reaches a high point when, during a ceremony in which she is supposed to send a man to jail for life for stealing clothes for his children, she gives him her jewelry to pay off his debt. Her actions infuriate the king, however, and he tells Maxon that he should send all of the remaining girls home because none of them are fit to be his wife. Maxon resists his idea and, later, his father decides that it is not feasible when the Italians want to form an alliance and want the royal family, and America, to visit. He still wants to eliminate America or make her bend to his will. He comes up with the idea for her to read propaganda ads so that he benefits from her popularity. He says that if she does not do it, she cannot marry Maxon. He lets her think about it, but when America's father dies, she is able to go home to her family before giving an answer. While she is there, she reads a letter her father left her and realizes that he was a Northern rebel. She is also provoked by her brother, Kito, into revealing to her other family members, and her maid Lucy, that she and Aspen had dated. She says that she will tell Maxon when she returns.

Maxon calls her back to the palace early because he has chosen his bride. It is America. However, before the official announcement is made, he sees America with her hand on Aspen’s chest. This confirms his belief that Aspen is the man America has been trying to get over. He decides to marry Kriss instead. Both girls are at the engagement party sitting next to Maxon when a guard kills Celeste. America realizes that he is a Southern rebel in disguise. He tries to kill her, but Maxon takes the bullet instead. Aspen gets Kriss to a safe room. Maxon tells America how much he loves her before Aspen takes her to a safe room against her wishes.

August and a palace guard, who America now realizes is a Northern rebel, come to let her out. They take her to the hospital because she is in shock. When she wakes up, she thinks that Maxon is dead, but finds an injured Aspen who tells her that Maxon is alive and is now the king. The king and queen both died as did her head maid, Anne. She also finds out that Aspen and Lucy love each other. America goes to see Maxon. He tells her about his plan to eliminate the caste system and proposes to her, again. She says yes and the two get married.