Vincent Machot knows his life by heart. He shares it between his hair dressing salon, his cousin, his cat, and his too-invasive mother. But life sometimes holds surprises, even for the most prudent of people... He crosses paths with Rosalie Blum by accident. She is a mysterious and solitary woman whom he is sure he has already met. But where? Intrigued, he decides to follow her everywhere, in the hope of knowing more about her.

Clem follows the life of a young teenager, Clémentine, who becomes a mother at the age of sixteen, at the centre of tensions between her parents and Julien, the father of her child Valentin. It deals with the problems of teenage life and that of a mother with a strong personality.