Quebec, in the sixties. Agathe, a gifted child, is asthmatic and lives in the suburbs with her mother Thérèse (Larissa Corriveau), a melancholy artist. At night, the whistle of a train fuels Agathe’s fantasy of a parallel world. As a teenager in the ’70s, she discovers the bohemian scene and meets Frank (Lennikim), a sci-fi writer. His story will take the teenager on an unusual journey, beyond the borders of the world, towards “the great unknown”.