Amona, a precocious 10-year old with overly twee emotional and intellectual tendencies, is given a very special Diary by her gram, a beloved but sarcastic and curmudgeonly figure whose past has more than a few elements of "tell you when you get older." Gram advises her to write in it every day, but Amona discards the book under a pile of shoes in the closet, until two years later, her gram dies on the eve of Amona's 8th-grade graduation.
In the weeks after her gram's funeral, Amona finds that old, discarded Diary, and in the first weeks of the summer before high school, she begins writing in it. Several weeks pass, in which she finds comfort and inspiration writing on the lined, illuminated side of each page - varicolored pages, each page with a different border of intertwined figures, or trees, or insects, or a who-knows-what-it-is design. She fills all the lines and then turns the page, to see what the next page will bring. One day, she goes back to read over what she has written, and recieves the shock of her life.
On the unlined side of each page, the diary has been writing her back.