Fat girl Tracy (Nicole Blonsky) grew up in an ordinary American family in the 1960s. She was fascinated by a TV talent show dance program and dreamed of standing on the stage to shine. However, Tracy's mother lacked confidence because of obesity since childhood, and often worried that obesity would be a stumbling block for Tracy. Unexpectedly, Tracy's outstanding performance in the show suddenly opened up her future. Even everyone liked her more than Miss Amber (Brittany Snow), who was originally very favored. In addition to joy, Tracy ushered in a sharp turn in her career. On the one hand, in order to maintain her position, Amber did not hesitate to use despicable means to turn the tide, and even seduced Tracy's father, causing family discord. On the other hand, the society strictly implemented racial segregation at that time, and Tracy was also caught in a racial struggle. The dangerous situation could destroy her career prospects at any time.