Mab Mitchell is technically the eldest of the 16-year-old Mitchell triplets and one of the novel’s protagonists. The three girls are closely bonded, and their household is a happy one. Mab is in Track A at Bourne Memorial High; at other schools, she would be considered one of the “advanced” or “gifted students” (10). Bourne does not use such labels, but the students are nonetheless aware of their own ability levels. Just like her sisters, Mab is highly intelligent and hopes to attend college, even though she is not sure how she can afford it or whether she will even be able to keep up with students from schools that have more resources and a better curriculum. She and her friend Petra have begun studying for the SATs, and they often volunteer their time as tutors after school.

Mab, like many adolescent girls, is beginning to have crushes on boys, and although she dislikes River Templeton at first, the two soon begin dating. Their relationship is not without conflict, however, for as the grandson of the man whose chemical company poisoned Bourne’s water supply (and the son of the company’s current owner), River inevitably represents an entity that has always been a force for evil in her family’s life.