The Question and Answer section for Into the Wild is a great resource to ask questions, find answers, and discuss the novel.
The setting is an important part of the plot. Chris' death can be seen as a result of his decision to "disappear" into Alaska. The terrain, the climate, and the season each served to work against him.
Initially Gallien thinks McCandless is "another delusional visitor to the Alaskan frontier". He thinks that some people have a romantic vision of the Alaskan wilds when, in reality, it is harsh and uncompromising.
The summaries GradeSaver has are at the link below. We typically do not do summaries on this short answer forum.