Viola Hastings, played by Amanda Bynes, is a dedicated high school soccer player at Cornwall, where the girls' soccer team has unfortunately been disbanded. Passionate about sports and particularly skilled at soccer, she finds herself in a tough spot when her request to join the boys' team is denied by the sexist coach Pistonek (Robert Torti). Feeling discouraged, Viola splits with her boyfriend Justin, who scoffs at her ambition to play for the boys.
Meanwhile, Viola's twin brother, Sebastian (James Kirk), needs a favor. He is set to enter Illyria as a new student but has to miss it due to a band contest in London. Sebastian enlists Viola to cover for him, telling their parents, who are divorced, that he’s sick. Not thrilled about this plan, especially since Sebastian was kicked out of Cornwall for skipping, Viola makes the bold decision to impersonate her brother and join the boys' soccer team at Illyria, coached by Dinklage (Vinnie Jones). Her ultimate goal? To lead her team to victory and crush her ex-boyfriend Justin's dreams on the rival Cornwall team.
With some help from her stylish friend Paul (Jonathan Sadowski) and her girlfriends, Viola transforms into the eccentric “Sebastian.” At Illyria, she becomes roommates with the charming Duke Orsino, portrayed by Channing Tatum, who is blissfully unaware of the truth. When Duke discovers tampons in "Sebastian's" backpack, he assumes they're for nosebleeds, which adds a comedic twist to their interactions.
During soccer tryouts, Viola lands a second-string position, forcing her to come up with creative excuses to avoid removing her shirt, claiming an allergy to the sun. To improve "Sebastian's" image among the guys, her friends Kia (Amanda Crew) and Yvonne (Jessica Lucas) flirt shamelessly with him, which leads to a comedic series of events when "Sebastian" garners unwanted attention from Monique (Alex Breckenridge), who is dating the real Sebastian.
As "Sebastian," Viola finds herself in a complicated love triangle. Olivia (Laura Ramsey), her lab partner, develops a crush on "Sebastian," while Duke finds himself falling for both Olivia and Viola. In a twist of fate, Duke asks "Sebastian" for help on his approach to girls, leading to heartfelt moments and misunderstandings between the trio.
The chaos ensues at the Junior League carnival where viola, juggling both identities, must evade her mother and Monique while still supporting Duke. A fateful kiss at the kissing booth between Duke and "Sebastian" (a.k.a. Viola) ignites jealousy when Justin arrives. This leads to a confrontation set to unfold on the soccer field.
Complications arise with the real Sebastian unexpectedly returning home early, turning the entire charade upside down. As "Sebastian," Viola has to run to protect her identity amidst mounting chaos. The climax builds until Principal Gold (David Cross) exposes Viola's ruse during an important game against Cornwall. In a surprising twist, the actual Sebastian proves his identity in a shocking manner, prompting Viola to finally reveal the truth and battle for her place on the field.
In a triumphant turn of events, Illyria scores a victory thanks to Viola's skill, challenging the sexist coach's beliefs. As the dust settles, Viola invites Duke to the debutante ball where their feelings culminate in a heartfelt kiss. The film concludes with Viola and Duke proudly showcasing their skills on the Illyria soccer team one year later, both firmly placed on the first string, celebrating a newfound love and friendship.
