Addie Coleburn, fresh out of the sixth grade, is spending the summer at her grandmother's house in Syracuse with her mother and brother. Kimi Takahashi, a girl who lives up the street, invites Addie to go to the park and play lacrosse. Addie hasn't the first clue what lacrosse is and would rather sit on Grandma's front porch eating potato chips, drinking sodas, and reading books. But then again, spending the summer dealing with her younger brother isn't that appealing either. So she reluctantly goes to the park with Kimi. Within a week, she's hooked on lacrosse. Although she's overweight and can't keep up with the faster, stronger girls, she loves the game. Now she has to find a way to lose her excess weight and lose it fast or risk getting cut from the team.