As the ninth ''Asterix'' album opens, Vitalstatistix receives a letter from his brother Doublehelix in Lutetia; he is sending his son Justforkix to the village for a holiday, feeling that life in Lutetia is making the lad soft. 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 (as Redbeard and his pirates learn the hard way when they try heading north to escape the Gauls), 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 you wings', and mistakenly believes that fear will enable him and his men to fly. They decide to start their educational voyage in Gaul.
Asterix and Obelix start Justforkix' training by getting him out of bed at the crack of dawn (which is usually when he ''goes'' to bed) and taking him down to the beach; as Asterix ponders how to proceed with the training, a terrified Justforkix spots the Normans' ship, and is stunned when Asterix and especially Obelix seem excited by the prospect of a Norman invasion. His attempt to raise the alarm in the village goes just as badly; Vitalstatistix simply asks Asterix and Obelix to do a bit of reconaissance, and Getafix decides to brew a bit of magic potion, just in case. Justforkix' mood deteriorates when Asterix and Obelix report that the Normans have landed, and, quite apart from being alarmed, are splitting their sides laughing at the invaders' names all ending in "-af". The terrified Lutetian tries rousing the other villagers into fleeing, but instead just gets them fired up at the prospect of having someone other than the Romans to thump.
Timandahaf sends one of his warriors, Nescaf, to do a bit of scouting of his own, and he overhears Asterix and Obelix on their way out boar hunting, and boasting about their own lack of fear, but the Norman's mood improves when Justforkix catches up with them and sobs about how terrified he is - and sours again when Asterix and Obelix are able to calm him down. Timandahaf decides they need to get Justforkix alone to teach them the meaning of fear, and they're in luck - he has decided to return to Lutetia, but a souvenir menhir from Obelix breaks his chariot, and he is kidnapped while attempting to repair it. Unfortunately, the Normans can't get their heads around the idea that ''they'' are the ones frightening ''him'' instead of the other way round, and they tie him up on the beach until he can scare them - if he fails, they'll throw him off a clifftop, and watch his fear make him fly.
In the meantime, Asterix and Obelix have found Justforkix' broken and deserted chariot, and Vitalstatistix sends them into the Norman camp to get answers; inevitably, a fight breaks out, and Asterix and Obelix are surprised to see that the Normans take more of a beating than the Romans (thanks in part to the reviving effect of their drink of choice, apple brandy) - a comparison emphasised when a Roman patrol shows up and gets caught in the crossfire. When Asterix finally gets Timandahaf to explain what they want with Justforkix, he gets an idea and sends Obelix back to the village to fetch something that he says will really scare them, while Asterix himself stays behind as a second hostage.
The "something" for which Obelix has been sent back to the village is the bard Cacofonix - except he isn't in the village. Fed up with having his talents unappreciated, he has taken Justforkix' advice and set out for Lutetia, but Obelix and Dogmatix are able to follow the trail of people complaining about the horrible noise and catch up with the bard, who agrees to return for Justforkix' sake (and insists on entertaining the unfortunate Obelix and Dogmatix with a version of "This Old Man" that goes on for at least 157 verses).
Meanwhile, Timandahaf's patience has run out, and he decides to have the two hostages executed. Justforkix manages to gain himself a stay of execution by offering to scare the Normans, but his attempts all fail miserably, and the Normans Firsthaf and Secondhaf prepare to throw him off the cliff... until a magic potion-strengthened Asterix breaks out of his chains and comes to the rescue. Seeing his friend outnumbered moves Justforkix to get over his own fears and help out, if ineffectually. Fortunately, he buys them just enough time for Obelix and Dogmatix to return with Cacofonix; the Normans initially laugh off the idea that the bard will scare them... and then the singing starts, and they are begging him to stop, as they can't stand anymore! Just the thought of listening to Cacofonix's voice makes them ill, which Asterix declares evidence that they now know the meaning of fear. The ecstatic Normans plan to express their gratitude by massacring the Gauls and sending them to Odin's table in Valhalla, but Justforkix has well and truly overcome his fear, and leads his fellow countrymen in a fight against the Normans, whose newly-gained knowledge of fear prompts them to beat a hasty retreat over the cliff and back to their ship... during which they 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 (as Redbeard and his band once again learn the hard way). 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: ''Asterix and the Vikings'', which took the basic story and added a few new elements.
* ArtisticLicenseGeography: The AnimatedAdaptation has Asterix chase the Vikings back to their home by following the North Star. Sailing due north from Asterix's village would take him to England, not Scandinavia. Sailing from Northern France to Viking territory and back in a little day sailer in under a month is also highly unlikely.
* 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.
* ComicallyMissingThePoint: When Asterix knocks the decurion of the Roman patrol flying and overeager legionary Oleaginus charges into Obelix in retaliation, Obelix stops beating up the Norman in front of him (or, rather, making the Norman beat ''himself'' up by manipulating his club-holding arm) and starts smacking the living daylights out of Oleaginus. The puzzled Norman says "What about me?", and Obelix apologises: he didn't realise the Norman wanted a go at beating up Oleaginus as well, and he obligingly holds out the hapless legionary, offering to split him down the middle.
* ConvectionSchmonvection: The climax of the AnimatedAdaptation takes place in a snow-covered cliff riddled with steam vents. Despite there being enough steam emitted to launch a man hundreds of feet in the air, the snow doesn't melt.
* 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.
* EngagementChallenge: In the AnimatedAdaptation, Timeandahaf promises his daughter's hand to the one who finds the Champion of Fear who can teach them to fly, inspiring Cryptograf to plot to secure that marriage for his son Olaf. Justforkix wins the challenge inadvertently by inventing hang-gliding.
* 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.
* EvilChancellor: Cryptograf in the AnimatedAdaptation.
* 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. The Vikings, in turn, think it's funny that the Gauls all have names ending in 'ix'.
* 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.
* PaintingTheMedium: Curiously averted. The Normans' dialect of Proto-Germanic is given in the same font as Gaulish, Latin, and Brittonic.
* 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.
* TokenRomance: The AnimatedAdaptation has Justforkix meet and fall in love with Timeandahaf's daughter Abba.
* TrainingMontage: The AnimatedAdaptation has one set to "Eye of the Tiger" in which Justforkix is literally tossed out of bed every morning so he can be subjected to an Obelix-designed workout regimen: lifting menhirs, running down wild boars, and punching pirate ships. The only thing Justforkix gets better at is the second part: he eventually gets fast enough to be able to safely run away from the boars.