Élise Lafontaine has a secret routine. Every morning and evening for many years, she has been waving at the express train that passes her house. One fateful day, she finds a letter from the train conductor in her garden and her lonely life is turned upside down. She engages in a promising correspondence through poetic and thoughtful letters where the two anonymous writers share their worlds with each other. But Elise’s fairytale is cut short when the train line permanently detours for a shorter route to Paris. Not willing to do without her daily delight, Elise prompts a daring escape from her comfort zone and sets out to find the train conductor.
