The books follows Georgia Nicholson, a 14-year-old girl living in Eastbourne, who is obsessed by the idea of being older and entering into a mature relationship. With the help of her "Ace Gang"—Jas, Ellen and Rosie—she manages to get the attention of Robbie, a new boy at her school.
Georgia and Jas plot to enter into relationship with Robbie, and his brother, Tom. Despite Jas being successful, Georgia realizes that Robbie is already in a relationship with Lindsay, the most popular girl in school. In order to win Robbie over, she bonds with him over their shared love of cats, using her cat Angus as bait.
In order to get snogging practice, Georgia employs the help of Peter Dyer, but he quickly becomes obsessed with her. Meanwhile, Robbie and Georgia get closer, but he does not take things further, leading Georgia to make him jealous by going out with Mark instead. When Robbie finds out, he is jealous but tells her he cannot pursue a relationship with her as she is too young.
Nonetheless, when Angus goes missing, Robbie finds him and tells Georgia he really likes her. The two enter into a relationship but this is cut short when Georgia’s dad, Bob, informs the family that they will be moving New Zealand.
