Set in the U.S. in an unspecified future, the book is told from the point of view of Klara, a solar-powered AF (Artificial Friend), who is chosen by Josie, a sickly child, to be her companion.

In the novel, the society has taken away pain and strife by converting to "Sameness", a plan that has also eradicated emotional depth from their lives. In an effort to preserve order, the society also lacks any color, climate, terrain, and a true sense of equality. The protagonist of the story, a 12-year-old boy named Jonas, is selected to inherit the position of Receiver of Memory, the person who stores all the memories of the time before Sameness. Jonas struggles with concepts of the new emotions and things introduced to him, and whether they are inherently good, evil, or in between, and whether it is possible to have one without the other.