Brook Gunderson may have a girl's name and a girl's skinny body, but no one can say he throws like a girl. As the star pitcher on his high-school baseball team in Lethbridge, Alberta, Brook (or "Gunner"to his teammates) lives for the provincial tournament and the occasional, highly elaborate practical joke. As baseball season moves on and the team starts to pull together, it seems like this might be the best summer of Brook's life.

But at home, things aren't going so smoothly. Brook's older brother, Frasier, is back after dropping out of college, and his busy parents don't seem able to help keep him on the right track. Brook escapes by spending more and more time with his friends until one last crazy stunt threatens to ruin his sporting ambitions—permanently.