Thirteen-year-old Zinnia is about to turn fourteen when her life is flipped upside down. With her parents on the brink of a divorce, Zinnia is sent to spend the summer with her eccentric great-aunts at their lake house away from her home in Manhattan. Zinnia arrives at her aunts' massive Victorian house with a heavy heart after a recent falling out with her best friend Charlotte, who betrayed her trust by showing the meanest and most popular girl in school a letter Zinnia wrote confessing her feelings for Charlotte. The aunts rely on practical magic, acceptance and old family friends to help heal their great-niece in more ways than one.

What Zinnia discovers on Ambrosia Hill is more than just her birthright to magic—she meets Billie, a girl who conjures feelings inside Zinnia that she can no longer deny.