Jorden Er Flad or The Earth is Flat is based on the play Erasmus Montanus, from the classical era in Danish literature, by Ludvig Holberg. Director Henrik Stangerup had the play translated into Portuguese, and adapted it for filming in contemporary Brazil. In this comic movie, a group of villagers have scrimped and saved to send their fellow villager Erasmus Montanus (Fausto Wolff) away for an education. When the boy returns to his village, he is stuffed full of book-learning of a kind which is of absolutely no use to those of the village. The boy, rather than seeing his situation clearly, continues to spout learned platitudes, including the incredible observation, "the earth is round," supported by nothing other than his authority as an "educated man." Understandably, his posturing provokes derision.

Monica, a naive schoolgirl from a suburb of Rio de Janeiro, meets Virginia, a former neighbor, now living in Copacabana. Influenced by her, she decides to take on a double life: in the morning she is the suburban girl, in the afternoon she attends a brothel in the South Zone. One day she meets Flávio, a friend and eventual lover of Virginia. Flávio falls in love with the purity of Monica and wants to drive away her friends, for considering Virginia a bad company for her beloved.

Kiko and Duda, circus workers, get into a big mess when Kiko is mistaken for the trampist Sinbad. The bumbling boy is then abducted by the minions of the magician Ali Tuffi, who already has in his power the genius of the magic bottle, but they need the trapeze artist, descendant of the true sailor, to locate the philosopher's stone with which he will become a man very rich, with lots of fortune and power. In an attempt to help his friends, the real trampist Simbad and his girlfriend Luciana also end up being held prisoner on the bandits' ship. After a confusion, everyone will stop on an island full of dangers, where the stone is hidden.