Enid Blyton's The Naughtiest Girl series follows the adventures of Elizabeth Allen, a spirited and often rebellious young girl sent to Whyteleafe School, a progressive boarding school. Initially spoiled and strong-willed, Elizabeth plans to be as naughty as possible to get expelled. However, the school's unique atmosphere, where students are encouraged to manage their affairs and take responsibility, starts to influence her in unexpected ways.

Over the series, Elizabeth's character undergoes significant development. While she remains headstrong and occasionally mischievous, she learns the importance of friendship, fairness, and empathy.