In northern France, Juliette grows up alone with her father, Raphaël, a veteran of the First World War. Passionate about singing and music, the lonely young girl meets a sorceress one summer who promises that scarlet sails will one day take her away from her village. Juliette never stops believing in the prophecy. Freely inspired by the tale "The Scarlet Sails" by Aleksandr Grin, Pietro Marcello's film blends music, history and folklore, bordering on magical realism.