Vitalstatistix's nephew Justforkix is visiting from Lutetia, and Asterix and Obelix are put in charge of his training. When Justforkix arrives, it's the typical city boy vs country folk situation, but Justforkix does hit it off with one villager - Cacofonix. Justforkix actually likes his music, and suggests the bard would find better audiences in Lutetia.
Meanwhile, far, far up north lies the country of Norse men, or Normans. The Normans have no fear, which is a problem, as this means no fear of authority and thus no discipline. Their leader Timandahaf decides that he and his men must learn fear, as they pride themselves at knowing everything. Plus, Timandahaf has heard that 'fear lends wings', and mistakenly believes that fear will enable him and his men to fly. They decide to start their educational voyage in Gaul.
While on the beach, Asterix, Obelix and Justforkix spot the Normans' ship. Much to Justforkix's confusion, Neither Asterix, Obelix, nor the rest of the village is worried about the Normans. If anything, they're excited! But Justforkix isn't - he's terrified of the Normans. However, when he relates this to his trainers, a Norman is nearby. It doesn't take long for Justforkix to be kidnapped by the Normans. Asterix and Obelix go to the rescue, and upon learning what the Normans want, Asterix sends Obelix back to bring Cacofonix. Upon learning of Justforkix's plight, the bard agrees to help.
Meanwhile, the Normans get impatient, and decide to have Justforkix show how fear lends wings- by throwing him off a cliff! Asterix downs a Magic Potion and takes on the Normans. Seeing his friend outnumbered moves Justforkix to get over his own fears and help out, if ineffectually. Luckily, Obelix returns with Cacofonix. At Asterix's urging, the bard gives a concert to the expectant Normans, and sure enough they don't want to hear anymore. Just the thought of listening to Cacofonix's voice makes them ill, which Asterix declares that they now know what fear is. However, the Normans soon learn that fear does ''not'' lend wings, and what's more they're now too fearful to fight or even work their ship!
Back at the village, Justforkix is now more willing to go about his training under Obelix. Asterix asks Getafix if fear has any use, and the wise druid states that only when one has overcome their fears can they truly be courageous. Meanwhile, the Normans manage to get over their own fears, becoming fiercer, at the expense of a certain pirate crew. Before Justforkix leaves for Lutetia, the village holds one of their ending feasts, and Cacofonix is allowed to sing for his part in the boy's rescue.
* AnimatedAdaptation / AdaptationExpansion: ''Asterix and the Vikings'', which took the basic story and added a few new elements.
* ArtisticLicenseHistory: The Normans only started their invasions in the early Middle Ages. Lampshaded when their chief states they'll leave the invasions to their descendants a few centuries later.
* BreakoutCharacter: Justforkix, sort of. While he never appeared in the comic again, he went on to star in a number of ChooseYourOwnAdventure novels.
* CharacterDevelopment: Justforkix. In fact, it's why he was sent to the village in the first place.
* EliteMooks: The Normans take something like three times as many hits to calm down as legionaries, a fight that surprises Obelix.
* EnemyMine: Obelix, still holding a Roman, politely offers it to the Norman he just beat up. The Norman happily accepts, and the Normans start attacking the Roman patrol as well.
* EveryEpisodeEnding: Subverted for the first time since ''Asterix the Gaul''; Cacofonix not only attends the banquet, but is allowed to perform in honour of his role in repelling the Normans (and to entertain the departing Justforkix). Instead, Fulliautomatix is tied to the tree, his ears stuffed with parsley to block out the bard's voice.
* FearlessFool: The Normans, to an extent. Because they can't feel fear, their society has a few problems with discipline, as nobody fears authority.
* GoneHorriblyRight: The Normans came to learn what fear was. They learned what it was, all right.
* HypocriticalHumor: Obelix thinks it's funny that the Normans all have names that end in 'af', as does Vitalstatistix, who shares the joke with Getafix, Cacofonix, Operatix, Acoustix, Harmonix, and Polyfonix.
* LeeroyJenkins: New legionary Oleaginus, blissfully unaware of just how dangerous the Gauls can be, insists on confronting them even as his fellow legionaries try to bury their discovery of their suspicious actions in red tape, and when the decurion is beaten up by Asterix, he charges straight into Obelix (and ends up the worse for it). He learns to appreciate the value of red tape as a way of avoiding the Gauls after this encounter.
* LiteralMinded: The entire plot gets started when the Normans hear the phrase "Fear gives men wings", and, being entirely fearless, decide to find someone who will teach them to be the greatest cowards around.
* LovableCoward: Justforkix, for a given level of "lovable." He finds his nerve during the story.
* RunningGag: Norman recipes being "food à la crème", the Normandy region being famous for its dairy products.
* ThrowTheDogABone: Not only does Cacofonix meet someone who likes his music, but in the end he's allowed to play at the usual banquet with his typical critic Fulliautomatix BoundAndGagged.