Angus Bethune is a 14-year-old boy living in Minnesota, who, despite his talents as a football player and in science class, holds deep insecurities about himself. His high school peers, led by the handsome Rick Sanford and his complacent cohorts(mainly jocks on the football team), regularly harass him for not being "normal," since he is pathetically overweight and is, in their view, "named after a cow." Because of this, Angus applies for Jefferson High School, a magnet school where he hopes to be free of the constant humiliation. Such infamy has shied his away from revealing his feelings to his secret crush, the blond cheerleader Melissa Lefevre, for fear that she will reject him, and because she is currently dating Rick. Rick, however, is not lost on his wish: As the ultimate prank, he rigs an election so that Angus and Melissa will dance together in the upcoming Winter Ball as King and Queen, respectively.Frightened upon learning this, Angus gets help from his best (and only) friend Troy Wedberg, his mother, Meg, and his narcoleptic grandfather, Ivan, who can be awaken by using his record player. His grandfather tells him about a dance move called the Irish Swoon that he claims is a guaranteed lady pleaser, but his fears that his largeness makes him an inept dancer and would embarrass both him and Melissa. To fix this, Ivan takes him to Madame Rulenska, where despite his best efforts he comes out worse than before (and injuring the hapless Madame in the process).One day after football practice, Angus opens his locker and sees that his favourite pair of boxers are missing. He and Troy learn later with their own eyes that their fellow quarterback Rick hoisted his boxers up the flagpole for the school to see, which then fly squarely onto passerby Melissa's face. Angus storms home in anger as the kids laugh at him, but Rick and company quickly kidnap Troy, asking him for anything that would embarrass him at the Winter Ball. In the trash cans, Rick asks for his help in embarrassing Angus at the dance. Troy refuses their request and tries to escape, only to break his arm as he trips to the floor while he gives the nerd an ultimatum.Meanwhile, Angus helps his grandfather prepare for his marriage to the young thirty-something named April. As much as he hates to admit it, he's actually happy for him. As he waits with Ivan in his room on the day of the wedding and confides with him his love for Melissa, he tries to wake him, but he quickly discovers that he is dead. Distraught, Angus opts to stay home for a few days time in which, for fear that Rick will hurt him even more. At the school bleachers, an unwilling Troy procures a videotape to him and his cronies. A bandaged, Troy confronts him about it in the park where Ivan and his friend were playing chess weeks earlier. Angus finally snaps and tells him that he did want to go to the Winter Ball with Melissa, but because his grandfather died, he resolved to stop wishing for everything and disappear by going to Jefferson.Later that week, while cleaning up from the wedding, Angus receives a box from April and opens it, revealing the plum tuxedo that he had earlier rejected. He realizes that his grandfather was right that he needs to stop fearing humiliation from Rick and stand up for himself or nothing would change. Resolved to grant Grandpa Ivan's wish, he rejects an interview from Jefferson which he applied to. He wears his plum tuxedo and marches to the school gymnasium, where the dance is held. Troy tries to warn him to turn around and walk away because Sandford has his humiliation set up for him. Angus refuses by telling him, screw Rick because he's tired of running away from every fight around him and that he would rather face humiliation than let the selfish jock win. He meets Melissa, and the two converse for the first time. As they are introduced to the students, Rick plays his videotape on the monitors, which shows Angus dancing with an inflatable doll. The students laugh while Melissa runs out of the gym in tears, and Bethune follows angry at Troy for his involvement with their enemy.Outside the gym, Angus apologizes to a hurt Melissa about the tape. However, she surprisingly shows how much she hates Rick, because he's very controlling and abusive to her and the other students. Melissa also reveals that she's bulimic and Angus understands very well. He tells her that he tried it once, but he was so hungry that he almost ended up eating his hand, which makes her laugh. Melissa reveals that she likes Angus, because despite being overweight, he's very kind, smart and treats other with respect. She also reveals those are good traits that the jock lacks, because Rick only cared about his looks more than trying to treat the student body with respect. Finding common ground, the two return to the gym and dance, even as she helps him out with some of the steps.After the two receive a mild reception from the students, Rick scolds Melissa, while Angus comes to her defense. It is here that he finally confronts him and petitions him to realize that there are in fact many people that don't fit his idea of "normal," and are unwittingly ostracized for it, and are fed up with the humiliation. However, Rick selfishly refuses his plea by replying "Whatever I am, it's something you're never gonna be." to which Angus replies "Thank God!" basically saying that he would rather be an awkward large kid with a kind heart, instead of a malevolent, selfish and vain jerk like him. The students congratulate Angus for taking a stand against Rick. Melissa dances with him and Troy enacts a little revenge on the jock by breaking his nose with his cast and impressing his crush.In the end, Angus rejects the offer to transfer to Jefferson High School to which he first applied after he takes his stand against him. He realizes that his grandfather was right that he doesn't have to run away anymore making him the victor in his battle with Rick and his peers. It is also leaned that he has been suspended for his video prank against him during the Winter Ball dance.