To eight-year-old Grace Davitt, her mother, Anna, is a puzzling yet wonderful mystery. This is a woman who has seen a sea serpent in the lake, who paints a timeline of the universe on the sewing-room wall, and who teaches her daughter a secret language which only they can speak.

For Grace's father, however, the only truth is science, and increasingly he finds himself shut out by Anna as she draws Grace deeper and deeper into a strange world of myth and obsession.