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.

Claire and Maurice have to take the whole family to Claire's father's funeral. This tightly knit family is not only composed of Claire's vegetarian son, Alex, who's secretly fond of Maurice's daughter, Lucie, the teenage rebel, but also Claire's brother, a poet living under his sister's roof; without forgetting young Prune, Claire and Maurice's daughter, who will develop a passion for the country's emblematic cows. They must all strive to get along during the road trip to Willouby.

Doctor Knock is a former thug who has become a doctor and arrives in the small village of Saint-Maurice to make his fortune according to a particular method. It will make the villagers believe that they are not as healthy as they might think. It is thus that he will find in each one an imaginary symptom, or not, and thus will be able to exercise his profession lucratively. Under his seductive looks and after gaining the confidence of the village, Knock is on the verge of achieving his ends. But his past catches up with him and an old acquaintance disrupts the doctor's plans.

Lui, a struggling author with a heart condition, and his wife Elle, a retired psychiatrist, find their idyllic life shattered when Elle begins to succumb to the effects of dementia.