With Gaumont not happy about the last film Asterix and the Big Fight, Extrafilm did Asterix Conquers America (German: Asterix in Amerika) alone. Although the film was made in Germany, it has the distinction of being the first Asterix film to be animated in English first and then dubbed in other languages later.
During a brawl in their Gallic village, the magic potion that gives the heroes Asterix and Obelix their superhuman power tips over. Before the druid Getafix can make another brew, the Romans capture him and catapult him into space from their galley at the edge of the word. They believe the earth is flat. Asterix and Obelix set out after Getafix. They end up in America, where Indians, who already hold Getafix prisoner, capture Asterix. Obelix, who has become seperated from his friend, saves a young woman from being trampled by a stampeding herd of bison. The young woman is from the tribe who have captured Asterix and Getafix and is the daughter of the chief Asterix and Getafix are freed and the majority of the Indians soon accept the three Gauls as friends, after the chief's daughter tells them of how Obelix rescued her. However, the medicine man has designs on their magic potion and Getafix has to use every trick in the book to protect its secret formula. The three Gauls finally defeat the wicked medicine man and sail back to Gaul.On their return home they find their village burned to the ground and its inhabitants abducted. Our heroes free their friends, tear the Roman camp apart and send Julius Caesar on his merry way.
The film is an adaptation of Asterix and the Great Crossing (French: "La Grande traversee"). It differs from the book in a few aspects, chiefly in that Getafix joins Asterix and Obelix in the New World. Getafix tells the other two Gauls that they are in "the hidden land of Indiana", which means that unlike in the book the Gauls do not believe that they are on an island off the coast of Gaul and do not mistake the Indians for mercenaries in the Roman army. The fat and unattractive chief's daughter of the book (who Obelix is keen to avoid marrying) is replaced by a tall, slender and beautiful young woman. Significantly, the vikings do not appear in the film.
A book adaptation, in text form rather than comic strip form, credited to Albert Uderzo was published under the original French title "Asterix et les indiens".