Billy Kennedy stars in this made-for-TV adaptation of David Walliams' children's book.

Despite being the star striker on his school's football team, 12-year-old Dennis Sims feels out of place at school, and still misses the mother who left left him and his brother John after divorcing their dad).

When aspiring fashion designer and fellow classmate Lisa  recruits him to model a dress for her, Dennis decides to wear it to school and adopts the guise of a French girl named Denise but is quickly found out and expelled by his strict head teacher.

But with the school's football team on a downward spiral without him, Dennis and Lisa try to come up with a creative scheme to get him back in school and back on the team.