Gene has a great deal of ambivalence about his return to Devon. He has a certain amount of nostalgia for the school of his boyhood, a place where he clearly had times of great joy. But there is an atmosphere of darkness in the beginning section. It is raining, cold, and gloomy. That is the dominant feeling for Gene on his return.
Why does he return? Gene's time at the school was a time of great turmoil, the war to which these young men were going, and a time of great tragedy, the death of Finney. Gene was responsible for Finney's death, he being the person who caused Finney to fall from the tree. The war and Finney's death have haunted Gene, and he is returning to confront his demons and perhaps to atone. You will notice that the specific places he wishes to see are the tree from which Finney fell, and the steps that Finney fell on. In combination, these are the scenes that led to Finney's death.
You might want to ask whether Gene is a better person than he had been while he was a student at Devon. Does he see the past more clearly or does he take more responsibility for his past actions? Is he still making excuses for himself? Does he forgive himself for what he did? Or is Gene more blameless than we think because Finney was a risk-taking kind of character who would have died no matter what Gene did or did not do? As this return to Devon is meant to show how we grow (or not), this is an opportunity for you to consider as you go back in time with Gene in the story whether his journey back was a productive one.