Later, she worked as a communications officer for a city council in Isère, focusing on energy and climate issues.
After writing four novels, Mélissa Da Costa decided to self-publish two of them on the platform Amazon, but they didn't find much success.
The novel, later titled Tout le bleu du ciel, which deals with early-onset Alzheimer’s disease and tells the story of a young man with a terminal diagnosis who embarks on a journey with a stranger, achieved significant success in paperback.
[8][10] In January 2023, Mélissa Da Costa was listed among the ten best-selling French authors of 2022 by Le Figaro.
[11] In 2024, according to a report by Le Figaro, Mélissa Da Costa became the most-read author in France, surpassing Guillaume Musso, who had held that position for twelve years.