In her diary, middle school student Jamie Kelly describes her life at home and at school, including her attempts to triumph over her nemesis, the beautiful and popular Angeline.

Jamie Kelly shares with her diary who likes her, that she likes Hudson, and that Hudson likes someone else at Mackerel Middle School.

Jamie Kelly writes in her diary about her social studies teacher, Mr. VanDoy, the budding relationship between her Aunt Carol and Assistant Principal Devon, and the real story behind Isabella's detention.

While preparing for her aunt's marriage to her school's assistant principal, Jamie Kelly still manages to document in her diary all of the stupid things her archrival Angelina does, which is most relevant because they will soon be cousins.

Jamie is upset because she is now automatic friends with her old enemy Angeline, and so she tries to find something that she and her real friend, Isabella, can do together for the school talent show without Angeline.

Something strange is happening at Mackerel Middle School, Jamie and Isabella are friends with Angeline, Jamie can understand boys, it must be superpowers.