Fifteen year old Charlie is coping with the suicide of his friend, Michael. To lessen the fear and anxiety of starting high school alone, Charlie starts writing letters to a stranger, someone who he has heard of but never met in person.
At school, Charlie finds a friend and mentor in his English teacher, Bill. He also overcomes his chronic shyness and approaches a classmate, Patrick, who, along with his step sister Sam, befriend Charlie and take him under their wing.
During the course of the school year, Charlie has his first date and his first kiss, he deals with bullies and makes friends, loses them, then gains them back. He creates his own soundtrack thourgh a series of mix tapes full of ironic songs, reads a huge stack of classic books, and gets involved in the school production of, the Rocky Horror Picture Show.