Following a fall during mistletoe picking, Druid Getafix decides that it is time to secure the future of the village. Accompanied by Asterix and Obelix, he undertakes to travel the Gallic world in search of a talented young druid to transmit the Secret of the Magic Potion.

Paris, Montmartre, 1883. Seraphine, 12 years old, leaves a monotoneous life with Jeanne, the grumpy seamstress who raised her. She is obsessed with finding out who her parents were. Flanked with Mistigri, a street child whom she takes under her wing, Séraphine retraces the secret of her origins and finds it in the battles led by the people of Montmartre.

Romain, a handsome young man in his thirties, only thinks about his work and never reveals his emotions. He can't manage to "flirt" with girls. His older brother Luc, who has become a screenwriter, is homosexual and never stops putting his brother down. However, the two brothers get along better than they seem to. Their father has a neurodegenerative disease and must be placed in a specialized institution. This ordeal will allow Romain to better understand himself as a man.