Following the death of her grandmother, reluctant heiress Madilyn Marak agrees to stay with her grandfather at the estate for the summer. While there, she finds a diary—The Apple Diary—written by her great-grandmother Isabel, telling the story of a long ago love affair with a woman named Lorah.

After reading about the affair, in the summer of 1933, Madilyn feels a bond with the two women and is determined to bring Isabel's beloved orchard—which had fallen into ruins—back to life again.

The normally quiet and reserved Madilyn finds a new joy in life as she becomes friends with the outgoing and energetic Dylan Hayes who has come to live on the property and replant the orchard. As she is transformed from a stoic and passive heiress to a happy and spirited woman, she realizes the similarities of her journey and that of Isabel's.

Like Isabel, will she marry a man she doesn't love? Or will she find the strength that eluded Isabel and follow her heart?