Magic's Child — Justine Larbalestier

In the third installment in the Magic or Madness trilogy, the people Reason Cansino loves most are all in danger. Reason's mother, Sarafina, has disappeared from the mental hospital in Sydney with Reason's evil grandfather, Jason Blake. Jay-Tee, the closest thing Reason has to a best friend, has used all of her magic and faces death at any moment. Only Reason can find the answers within her family's magic to save everyone who matters most to her.