Epigraphs are like little appetizers to the great entrée of a story. They illuminate important aspects of the story, and they get us headed in the right direction.
A man shrieks in pain
Crying to the universe. Panic is abrupt.
The book starts out with a poem, which is fitting considering how many poems or creative writing pieces there are throughout the novel. When we hear that someone "shrieks" we're not exactly sure what's being referred to—but we soon find out with the newspaper article that follows.
The poem is a little preview of what's to come with the accident. Robbie gets trapped and all his friends hear him shrieking inside the burning car, unable to do anything to help him. All Robbie's friends can do is cry. The accident—the moment of "panic"—comes out of nowhere and changes their lives forever.
It's a pretty morbid way to kick off the book, but it clues us in to the fact that the book is going to deal with tough issues like death and anger, even before we so much as meet a single character.