Of course, pivotal to the plot of John Knowles's novel is Gene's return to Devon school where he seeks "a separate peace" long after the occurrences which great affected his life. In a type of examination of conscience and mea culpa, Gene relives the events of his time at the school and finally comes to terms with his actions.
Here are the key elements of the plot:
Gene returns to Devon School and recreates the setting of his youth as he recalls his time at this school.
Gene meets Phineas and, although he likes the boy, he misinterprets his insousiance and lack of pretense, believing that Finny is somewhat jealous of him. Gene becomes competitive with his new friends, as well as envious of Finny. He jounces the limb off which the Summer Suicide Society jumps; Finny crashes through other limbs and falls into the water of the Devon river. Despite his injury, Finny harbers no grudge against Gene, whom he still considers his friend. The war comes and the boys work jobs in place of men who have been drafted. Leper joins the army, but later goes AOW and is released with a Section 8 for a mental cause. But Finny ignores the war and lives in his world of the Winter Carnival, providing the boys a "liberation ...from the gray encroachments of 1943."
Gene is trapped into a trial regarding Finny's accident and accused: "The one who moved first shook the other one's balance!" The spoken truth is too much for Finny who runs from the room, slips and falls down the staircase, fatally injuring himself.
Gene tells Finny he is sorry for his action that night on the limb; they reach an understanding as Gene explains the cause of his action:
"Tell me how to show you. It was just some ignorance inside me, some crazy thing inside me, something blind, that all it was."
But, Gene lives yet with the guilt as he watches Finny be buried:
I could not escape a feeling that this was my own funeral, and you do not cry in that case.
Gene reflects upon the parallels of his private war within himself and with Finny along with the world war in which he has fought. He concludes that he killed his enemy--"if he were an enemy"--at school, not in the war. He also reflects that wars come from "something ignorant in the human heart."