Emotionally devastated after learning that she's secretly referred to as "The DUFF" (Designated Ugly Fat Friend) by the entire student body, high-school senior Bianca (Mae Whitman) dismisses the cautionary advice of her favorite teacher (Ken Jeong), turns her back on her longtime crush Toby (Nick Eversman), and enlists the help of charismatic jock Wesley (Robbie Amell) to help salvage what's left of her senior year. As the once-contented senior wages a monumental struggle to regain her confidence, she gradually turns her efforts toward knocking cruel class queen bee Madison (Bella Thorne) from her throne up on high..