Charlie, the fifteen-year-old narrator of The Perks of Being a Wallflower, has just entered his freshman year of high school when the book begins. Charlie is the eponymous “wallflower.” He is quiet and withdrawn, but he is also extremely observant and thoughtful, always paying close attention to everything going on around him, even if he is only a silent witness. Charlie writes the entire book as a series of letters to an anonymous “friend.” The reader never learns who this “friend” is, and the “friend” never writes back. Each letter begins with the greeting “Dear friend” and ends “Love always, Charlie.” Because the recipient of the letters never writes back, the novel reads like a series of diary entries.

When the novel opens, Charlie is grappling with two major traumatic deaths of loved ones in his past. The most recent death occurred last spring, when his only friend from middle school committed suicide. When Charlie was seven, his beloved Aunt Helen was killed in a car crash on Christmas Eve, which is also Charlie’s birthday. Although Charlie is nervous about entering high school, he soon finds acceptance from two main sources. First, his English teacher, Bill Anderson, recognizes Charlie’s talent for literature, and he takes him under his wing, assigning him extra books to read and essays to write over the course of the year. Also, Charlie begins to participate more in events, and he becomes friends with Patrick and his stepsister, Sam, who integrate him into their friend group. Charlie develops an enormous crush on Sam, which he tells her about, but Sam treats him affectionately. Patrick, who is gay, is having a closeted relationship with Brad, the quarterback of the football team. Sam kisses Charlie so that his first kiss can be from someone who loves him.

As the school year progresses, Charlie begins to come out of his shell somewhat, but Charlie’s life, his family life, and his friends’ lives become more and more complicated. The holidays are always a difficult time for Charlie’s family, because they bring up memories of Aunt Helen’s death. This year is no exception. Even though Charlie finds some solace in reading and re-reading The Catcher in the Rye, he still struggles to cope with his depression and with flashbacks of his time with Aunt Helen. However, Charlie’s acceptance by his friend group helps him become more at peace with himself. As Charlie becomes more mature, his relationship with his sister also deepens. Charlie’s sister has an abusive boyfriend. Charlie tells Bill about the boyfriend, and Bill reports it to their parents, which makes his sister mad at Charlie. But when Charlie’s sister becomes pregnant, she decides to have an abortion, she trusts Charlie to drive her to the clinic.

After Charlie performs as Rocky in one of his friend group’s regular viewings of the film The Rocky Horror Picture Show, Mary Elizabeth, a smart, pretty senior in their friend group, starts dating Charlie. However, Mary Elizabeth is far more interested in Mary Elizabeth than in having a relationship. During a game of Truth or Dare, Charlie is dared to kiss the prettiest girl in the room, and he kisses Sam. Mary Elizabeth stalks out of the room in a rage. In solidarity, the rest of the group sides with Mary Elizabeth, and Patrick advises Charlie to stay away from everyone for a while until tempers cool down.

Brad’s abusive father discovers Patrick and Brad’s relationship, and Brad is sent to rehab. When Brad returns, he refuses to speak to Patrick. Patrick confronts Brad in the cafeteria, Brad makes a derogatory comment about Patrick’s homosexuality, and Brad’s football teammates beat up Patrick. Charlie jumps in and, in a whirlwind, breaks up the fight. His defense of Patrick wins back the respect of Sam and his friend group. Patrick is thoroughly depressed and he leans on Charlie for emotional support. Patrick gets drunk and kisses Charlie, but he apologizes, and Charlie understands that Patrick is lonely and doesn’t know how to handle it. Eventually, Patrick sees Brad kissing a strange man in the park, which helps Patrick pull himself together and move on.

At the end of the school year, Charlie becomes increasingly anxious as the prospect of all his senior friends moving away becomes more and more imminent. When Sam is packing to leave for her summer pre-college program, she and Charlie begin to make out and start to have sexual contact, but Charlie suddenly gets extremely uncomfortable. The sexual contact dredges up a repressed memory of his Aunt Helen molesting him as a child.

In an epilogue, Charlie writes a final letter to his “friend,” dated two months later, saying that his parents had found him naked in a catatonic state on the couch. They took him to a mental hospital, where Charlie eventually realizes that Aunt Helen had sexually abused him, but that he had repressed these memories. Charlie forgives the memory of his Aunt Helen, and the novel ends with Charlie writing that he is planning to stop writing letters and to start participating fully in his life.