The movie follows the adventures of Asterix, a clever and cunning warrior, and his best friend Obelix, a strong and burly man who fell into a cauldron of the druid's magic potion as a baby and has been permanently endowed with superhuman strength ever since. Together they lead their fellow villagers in resisting the Roman occupation of Gaul.
When the Romans learn of the druid's potion, they send Centurion Crismus Bonus to capture him and force him to reveal the secret formula. Crismus Bonus manages to capture the druid, but Asterix and Obelix come to the rescue. With the help of a magical scroll, they infiltrate the Roman camp and successfully free the druid.
Meanwhile, Caesar himself becomes interested in the power of the magic potion and orders his top scientists to create a replica of it. The scientists manage to create a potion that gives the Romans superhuman strength, but with a nasty side effect - the user becomes incredibly greedy and selfish.
In a final battle between the Romans and the Gauls, Caesar's army is defeated when they all consume the replica potion and turn on each other, leaving Caesar himself to admit defeat. The Gauls celebrate their victory, and Asterix and Obelix enjoy a feast of roasted boar, their favorite food.