Back at Devon, Gene finds Finny in the middle of a snowball fight with a bunch of other students. A few hours later, Gene asks Finny if it's okay for Finny to play around that way on his bad leg. Finny responds that when his leg heals it will be stronger than before.
Finny is still innocent and optimistic; the snowball fight is another childish version of war. Leper used to be this way, but the adult world crushed him. Gene has become cautious again.
Gene returns to his room and takes down some photos he had pasted up that were of a southern plantation he had implied to others was his home. Now that he feels he's growing up, he takes the pictures down.
Gene feels that he no longer needs a false identity to prop him up. He feels he's gaining his own identity.
Finny and Gene are back in their room when Brinker comes in and asks about Leper. Gene is vague, but Brinker guesses that Leper has gone crazy and expresses his sympathy. He then says, sadly, that their class at Devon now has two students who can't help the war effort, meaning Leper and Finny.
Brinker is intent on growing up, on facing reality, though he's no longer cruel about it. He just thinks it has to be done.
At Gene's prodding, Finny says once again that there isn't really a war, but this time he says it ironically. Gene realizes that the war is real, that everything that had sustained them during the winter, such as training for the Olympics, is just a dreamlike escape from the truth. Gene resolves to become "careful and self-preserving."
Once again Gene links his identity too closely to Finny's. When Finny admits the war is real, their shared "illusory" peace collapses. Gene's response is to become "careful and self-preserving," to act grown-up.
As time passes, most of the boys other than Gene enlist. One morning, Brinker suggests that Gene is delaying enlisting because he feels pity for Finny, and because some details of the accident that need to be "cleared up." Gene denies Brinker's claim. Brinker says that the only person who truly knows what caused Finny's fall is Gene.
Brinker reveals that his early jokes about Gene purposely injuring Finny to get his room had some substance behind them. Here he suggests that guilt now binds Gene to Finny since Gene made Finny his dependent.
Back in the dorm, as Gene does Finny's Latin homework, Finny says he began to believe in the war once he heard that it had made Leper "crazy." He adds that Leper definitely is crazy. He saw him lurking in the bushes outside the Devon chapel that morning. They decide not to tell anyone about it.
Finny's surrender to reality is a key shift in his identity and can be seen as the climax of the novel. Once Finny, the symbol and protector of innocence, acknowledges the war, the boys' fate is sealed.
Later that night, Brinker and three boys arrive at Gene and Finny's room. They all go to the Assembly Room, a large auditorium, in Devon's First Building. Brinker announces that they've gathered there to investigate Gene and to determine the truth behind the events of Finny's fall.
The mock tribunal echoes the tribunals that took place after WW2. Both sought the source of people's actions in order to determine guilt. Another link between rivalry and war.
They question Finny, who says he just lost his balance and fell, and that Gene was at the bottom of the tree. Gene agrees with the story, but then Finny remembers that they were both on the branch about to do a double jump. Brinker wishes Leper were there to comment on the differences between Gene and Finny's story. Finny admits he saw Leper that morning go into the school doctor's office.
Finny starts by trying to hide from the truth. But just as Brinker hoped, the tribunal forces him to confront it. Yet Finny still can't bring himself to entirely admit what happened.
The boys get Leper. Leper calmly says that Gene and Finny were on the branch together when Finny fell. He says the two moved like a piston in an engine: one pushed down first (Gene) and then the other rose and fell (Finny). But when Brinker asks who shook the branch, Leper refuses to answer and starts to seem crazy again.
Just as he can't face his hallucinations, Leper also refuses to face the truth.
As the tribunal tries to calm Leper, Finny stands and says he doesn't care what happened. When Brinker protests that they need to get the facts straight, Finny swears and rushes from the room in tears.
Brinker tries to make Finny face "the facts", i.e. reality, but Finny tries to assert his innocence, to hide from reality…
The boys hear the taps of Finny's cane as he runs down the hallway, and then a crash as he trips and falls down the marble staircase.
…but this effort leads to disaster, just as Leper discovered. Hiding from reality doesn't make it go away.