What is the main conflict in Vernon God Little by D.B.C. Pierre?

In Vernon God Little, first-time author DBC Pierre dares to go where many would not. The book is an absurdly humorous look at the misadventures of a Texas teen named Vernon Little whose best friend in the world has just killed sixteen of their classmates and himself. In the wake of the tragedy, the townspeople seek both answers and vengeance; because Vernon was the killer's closest friend, he becomes the focus of their fury.