A Separate Peace is a novel by award-winning author John Knowles. In this novel, Gene Forrester is a preparatory school student whose best friend is an outgoing and much beloved athlete named Phineas. Gene finds himself struggling beside Phineas and comes to the conclusion that Phineas wants to sabotage Gene so that he can be the star of the school. When this assumption proves to be false, Gene becomes confused. Gene causes an accident that will end Phineas' athletic career and derail his plans to join the war overseas. Gene will struggle with this single episode for months until finally Phineas learns the truth. A Separate Peace is a story of coming of age and of young men who struggle to find out who they are and what motivates them in a time of uncertainty and fear.

Gene Forrester returns to Devon, the preparatory school he once attended, fifteen years after graduation. As he walks across the campus, Gene begins to recall the year that changed his life. It was 1942, and Gene is part of the first summer term at Devon, a term designed to prepare the young men of his class for service in World War II. Gene's roommate and best friend is Phineas, Finny, an outgoing character who can talk his way out of just about any situation. Over this summer term, between classes, the boys create a club centered around those brave enough to jump into the Devon River from a tree and create a new ball game that centers on Finny's own unique rules.

One afternoon, Finny questions Gene's dedication to his studies. Finny accuses Gene of wanting to be the top of the class at graduation. As Finny jokes about this, Gene finds himself wondering if Finny is really jealous of him and if he has been sabotaging his studies in order to be the top student himself. This thought causes Gene to work harder at his studies and to ignore Finny's frequent pleas to go play. One day, Gene finally tells Finny that he is interrupting his studies. Finny is surprised and expresses a belief that Gene did not need to study, that his good grades came naturally to him. This confuses Gene and makes him angry with Finny. As the two boys prepare to jump from a tree limb into the river below, Gene shakes the limb and causes Finny to fall too early. Finny fractures his leg badly on the river bank below.

Gene finishes the summer term and returns home for a brief visit. When Gene comes back, he stops by Finny's house to speak with him. Gene tries to tell Finny that he caused him to fall from the tree intentionally, but Finny does not believe him. Gene returns to school alone as Finny recovers. Others seem to think Gene caused Finny's accident, but Gene brushes off the accusations and no one pushes it. In a few months, Finny comes back to school and the rumors are put to rest.

Finny returns to his same old antics, but they are tinged with some bitterness. Finny insists that the war is not real and he trains Gene so that he might take Finny's place in the 1946 Olympics. In the middle of the winter term, one of their friends, Leper, joins the Army. A few months later, during a winter carnival that Finny has planned, Gene gets a telegram from Leper telling him he has escaped. Gene goes to see Leper only to learn that he has gotten a discharge from the army for mental instability.

One of Gene's classmates has been bothered all along by Finny's accident. In the middle of the night, this boy and several of his friends kidnap Gene and Finny from their room and place Gene on trial. Finny cannot recall what happened that night, but Leper, who has returned recently to the school, remembers every detail. Leper tells them Gene shook the limb, causing Finny's accident. Finny leaves the hall in anger and falls down the marble steps.

Finny's leg is broken again. Gene goes to visit him, but Finny is angry with him. Gene returns the next morning to apologize again. Finny accepts his apology and tells him how he had wanted to join the military, but no one would take him now. The doctor comes and asks Gene to return later because they need to set Finny's leg. When Gene returns, he learns that Finny has died from escaped bone marrow that traveled to his heart. Gene graduates months later and enters the Navy, wiser and with the understanding that everyone deals with war in their own way.