After the storm passes, the soothsayer takes up shop in the forest, making prophecies in exchange for goods. Curious as to why people keep taking their fish/chickens/etc with them for walks in the woods, Obelix (who had argued with Prolix while he was in the village) goes into the woods and finds the soothsayer. While Prolix manages to distract Obelix, Asterix is confused by everyone's behavior, and goes into the woods as well, only to find that the soothsayer has disappeared. In fact, he has been taken by a Roman patrol from the camp of Compendium, the centurion at which, Arteriosclerosus, tells Prolix they are under orders to arrest all Gaul soothsayers. Desperate not to be locked up, he tries to explain that he's not really a soothsayer, he's just a con man living off of Gaulish gullibility. This gives the commander an idea.
Prolix returns to the village and claims that they are now cursed, and their village will soon emit a foul stench that will turn all that breathe it a noxious hue. Fearing the curse, the Gauls (apart from Asterix and Obelix) flee the village to a nearby island. Prolix returns to Compendium and reports that the Gauls have left.
While the Romans take the village, Asterix and Obelix wander the forest and run into the returning Getafix. After telling him what's been going on, the druid gets an idea to discredit the soothsayer. Shortly after the Roman commander sends a messenger to report all of Gaul has been pacified, a foul stench erupts over the village, turning all who breathe it a noxious hue. Fearing pestilence, the Romans retreat. Cacofonix, who had snuck back into the village to retrieve his lyre, also smells it and returns to the villagers to report the prediction had come true.
Asterix, Obelix, and Getafix meet up with the other villagers and explain that the source of the stench was a potion that Getafix had brewed, not any divine punishment. The Gauls return home (sinking a pirate ship that had anchored for the night between the island and the village on the way); however, despite everything, a lot of the village wives still believe Prolix is a real soothsayer (because he told them things they wanted to hear). Asterix suggests that they prove otherwise by giving Prolix a surprise. So Getafix brews up an extra-large batch of potion and invites the women to join the men in raiding the Roman camps.
At the camp, Prolix is utterly perplexed by his prediction actually coming true, and perpetually badgered by Arteriosclerosus' belief that the aid of a powerful soothsayer could propel him to the throne. Both these troubles are repelled by an unexpected horde of Gauls trashing the camp. They return from their expedition to find some Roman officials (there to investigate the report of the village being taken) in the village. Vitalstatistix has them roughed up and tossed out.
As Arteriosclerosus prepares to have the soothsayer locked up, the officials that Vitalstatistix had beaten up arrive and punish the centurion for falsely reporting the capture of the village by demoting him to common legionnaire. Outraged by the failures of his soothsayer, Arterioscerolsus orders his adjutant to arrest him, only to be told 1: If Prolix is a fake, then the standing orders to arrest soothsayers don't apply, and 2: Since the centurion is no longer an officer, he has no business giving orders to actual officers. As the now former centurion is set to sweeping the barracks, Prolix is ordered out of the camp. He vows to give up soothsaying, but Taranis remains sceptical...
The Gauls return home triumphant and have a celebratory feast.
- Acquired Poison Immunity: The foul-smelling concoction does not bother Unhygienix at all. Fulliautomatix suggests that it is because of his fish. Cue another fish fight.
- Artistic License – Statistics: Predicting one roll of two six-sided dice does not prove a gift of prophecy (especially not "7" which is the most likely outcome). Then again, neither centurion nor optio are as smart as they think.
- Art Imitates Art: The scene of Prolix "reading" the fish is drawn to resemble the 1632 painting The Anatomy Lesson of Dr. Nicolaes Tulp by Dutch artist Rembrandt van Rijn, with the fish taking the place of the cadaver in the original painting.
- Art Shift: The soothsayer „saying any old thing” has a photograph as a speech bubble.
- Big Eater: Obelix naturally assumes that when Impedimenta serves Prolix boar and milk, the boar is for him. Later, he is told to empty a cauldron and does so by drinking the contents.
- Blatant Lies: The various excuses of the villagers for taking food into the forest (e.g. taking chickens for a walk).
- Bolt of Divine Retribution: Possibly. “If I ever change my mind, may Taranis make the sky fall on my head.” Cue a thunderstorm.
- By-the-Book Cop: For most of the comic, the optio wants to lock up Prolix for being a soothsayer ("Orders is orders"). When he is put in charge and the Gauls have just proven that Prolix is a fake, he merely orders Prolix to leave the camp.
- Call-Back: When Prolix accidentally correctly predicts that a pair of dice will add up to VII, he explains that if he really were a soothsayer but wanted to prove himself a fake, he would have known the dice would add up to VII and would have predicted a roll of VIII instead. The none-too-bright Optio of Compendium is thoroughly confused by Prolix' defence, and in near the end of the book, he collars Prolix and orders him to make another prediction about a dice roll. This time, Prolix guesses VIII, but the dice add up to VII, which only confuses the Optio further.
- Comic-Book Time: Despite the intro still giving the year as 50 BC, at least a year has to have elapsed since the events of Asterix and the Goths, since Getafix is again attending the annual Druids' Conference in the Forest of the Carnutes.
- Continuity Nod:
- Continuity Snarl: Unhygienix is seen with a dripping net of apparently fresh fish. In Asterix and the Great Crossing he is proud of importing all of his fish from Lutetia by ox cart.
- Delusions of Eloquence: Arteriosclerosus' Optio tries to sound important and intelligent when he talks, but his tendency to drop his Hs, flout subject-verb agreement ("Orders is orders"), and expand his sentences with liberal visits to the Department of Redundancy Department make it clear how dim he really is. His report to Arteriosclerosus after first arresting Prolix illustrates this perfectly:Optio: On proceeding on patrol, for which you gave the orders to proceed with, we found this 'ere individual in a clearing, and after a caution he made a statement what we were not very satisfied with.
- Deus Exit Machina: Getafix isn't present for the first half of the book because if he was, the plot couldn't unfold the way it does (with Asterix as the Only Sane Man).
- Does This Remind You of Anything?: The scene where Getafix adds the final ingredient to the foul-smelling potion as the villagers stand in front is meant to look like he is taking a photograph of them.
- Dramatic Irony: On the page discussing soothsayers and their unreliability, an augurer is telling Julius Caesar that as long as Brutus is near him, he has nothing to fear (Brutus is even playing with a knife). Of course, we all know how accurate that was... Alternatively, the prophecy may be exactly correct. As long Brutus is on Caesar's side, he won't fall, but the moment he changes side... Then fall, Caesar.
- Dramatic Thunder: Prolix enters the chief’s hut to a well-timed thunderclap. Another accompanies his reveal that he is a soothsayer.
- Embarrassing Nickname: In the early days of their courtship/marriage, Impedimenta used to call Vitalstatistix "Piggywiggy". When Prolix tells her that Vitalstatistix will move to Lutetia to go into business with her wealthy brother Homeopathix (seen in the previous volume), she revives the nickname, much to Asterix and Obelix' amusement.
- Exact Words: Arterioslerosis reports the taking of the village by reporting that all of Gaul has been pacified.
- Externally Validated Prophecy: Very much averted. “And as long as Brutus is near you, o Caesar, you will have nothing to fear” (said while Brutus is playing with a dagger and grinning maliciously).
- Fear of Thunder: The usually fearless Gauls are afraid of a thunderstorm. Then again, it might be the prelude to the sky falling on their heads, which is the only thing they are afraid of.
- Foreign Queasine: Prolix predicts that Caesar Arteriosclerosus will be served preserved pigs’ ears.
- Gone Horribly Right: Every time Prolix needs to prove that he can/can't see the future, it goes exactly the way he doesn't want it to.
- Historical In-Joke: Once more involving Brutus. A short parenthesis about Soothsayers and how they are nothing but charlatans depicts one telling Julius Caesar that he will have nothing to fear as long as Brutus is near him.
- Insane Troll Logic: Vitalstatistix takes off his shoes, then has his shieldbearers carry him to the boat.
- Karma Houdini: In the end, Prolix gets away, without a scratch. However he does seem to have been a bit humbled by the experience and it's ambiguous on whether he will go back to his scammer ways. In the later album The Asterix and Obelix Birthday Book, we find Prolix up to his old tricks making preposterous predictions during Asterix' and Obelix' birthday party, to which he has inexplicably been invited (along with Squareonthehypotenus from The Mansions of the Gods, Redbeard and his crew, and Julius Caesar himself!); and while the Gauls are mostly tolerant, they are clearly skeptical.
- Morton's Fork: Prolix manages to impale himself on Morton's fork within seconds of being hauled up before Centurion Arteriosclerosus. He tries his usual method of playing on his victims' vanity by claiming to foresee the centurion's impending promotion, only to be told the Romans are under orders to arrest all Gaulish soothsayers. He tries to backpedal, claiming to be a charlatan... in which case he will be punished for insulting the centurion by pretending to foresee his promotion. Fortunately, he is able to fast talk his way out of this predicament... for a while.
- No Name Given: Despite being a prominent character in the story starting with Prolix' arrest, Artierosclerosus' rather dim-witted Optio is never addressed by name.
- No-Sell: Unhygienix is the only one unaffected by Getafix' foul-smelling mixture of gasses, because, considering his profession, he is used to such bad odors.
- Only Sane Man: Asterix is the only one in the village who doesn't buy that Prolix is a soothsayer, while everyone else blindly believes Prolix. Getafix doesn't believe in soothsayers either, but he's absent for the first half of the story.
- Opening Shout-Out: Arteriosclerosus’ message “All Gaul is occupied. – All?” quotes the opening page.
- Pet the Dog: After spending all the comic trying to lock Prolix, the Optio simply tells him to get lost.
- Phony Psychic: Prolix. The narration states that most so-called "prophets" were just fast-talkers taking advantage of people's gullibility. Which is then immediately parodied, as one of them is shown forecasting a "reasonable" view of the future (a picture of Uderzo's villa), while another is shown "saying complete rubbish" (a photograph of the then-under construction La Défense skyscraper district in Paris).
- Pun: Despite claiming to despise easy puns, Getafix calls the cauldron of stinking potion "the pollution to all our problems".
- Put on a Bus: From a Doylist perspective it's clear that the reason why Getafix was away for half the book was because Prolix wouldn't have been able to set up shop if he'd been around when the Soothsayer first arrived.
- Removing the Rival: The Roman soothsayers have conveniently predicted that Gaulish soothsayers are a threat to Roman security.
- Rolling Pin of Doom: Impedimenta’s weapon of choice.
- Running Gag:
- Across the comics: There are three fish fights, the first two in short succession. Prolix predicted the first fight, but as Asterix correctly points out, he simply realized that fights are common in the village, especially when fish is involved (fish fights are a Running Gag for a reason).
- Across the comics: Vitalstatistix falls of his shield. He ducks as the shieldbearers run through a doorway, but then fails to see a low branch.
- Across the comics: The pirates lose not one but two ships. One, because they trusted a soothsayer’s weather forecast, and the other because they trusted a mackerel’s entrails and got in the way of the Gauls returning from the island.
- Every time one of Prolix' predictions appears to come true following his arrest by the Romans, the Optio asks, "Do we lock him up, then?"
- Sarcasm-Blind: When Asterix asks where Obelix got the original idea of bashing up the Roman camp, Obelix replies that he is not just a pretty face.
- Sherlock Scan: Subverted, since most of what the seer predicts is either blatantly obvious or what he believes his audience wants to hear. When the Optio is reminded of where he used to live due to the hideous odor now floating over the village, Prolix innocently asks if he used to live near a tannery (as Prolix did), which causes the optio to try to arrest him (again) for being a real seer.
- The soothsayers in the exposition on soothsaying talk about Uderzo’s villa, respectively the then-under construction La Défense skyscraper district in Paris.
- Prolix “reading” the fish resembles the 1632 painting The Anatomy Lesson of Dr. Nicolaes Tulp by Dutch artist Rembrandt van Rijn.
- Springtime for Hitler: Prolix tries to prove that he is a fake by making a prediction on the outcome of a dice roll. He predicts a combined roll of VII, and believes that as he always loses at gambling, he should be safe in making an inaccurate prediction. However, the dice land on V and II, which add up to VII, so Arteriosclerosus orders his arrest. Of course, it was not a good choice, because seven is the most common result of rolling two six-sided dice (and not knowing that may explain why he always loses at gambling). Even worse in the animated adaptation where he predicts the coin toss would be neither heads nor tails, and the coin gets stuck in an amphora on the edge side.
- Suddenly Shouting: Bulbus Crocus’ voice is all flowers (literally) until he comes to what the “conquered” Gauls did to him.
- Tempting Fate: After being thrown out of the Roman camp, Prolix declares an end to his days as a soothsayer, and says that if he is lying, may Taranis strike him with a thunderbolt. Cue the sudden storm...