In Quebec in the 1960s, Agathe, an asthmatic child with a vivid imagination, lives in the suburbs with her mother Thérèse, a melancholic artist. At night, the whistle of a train fuels Agathe's visions of a strange parallel world. As a teenager in the 1970s, she discovers the bohemian scene and meets Frank, a young science fiction writer. His story will take the teenager on an unusual journey beyond the boundaries of the world, toward "everything we don't know."



