Answer:
Krakeur descibes to the readers how Chris McCandless embarked on a road trip and visted his hometown in El Segundo, California where he discovered a great secret.
He discovered that his father has been living a double life for many years, two years after his birth his father had another child with Marcia.
Chris decided not to disclose what he found out, he kept the secret to himself and then expressed his anger by withdrawing himself from everyone around him.
