The film The Mission is based on historical events that took place in South America in around 1750. The Guarani, an indigenous people who live in seclusion above waterfalls, resist conversion to Christianity. A missionary, nailed to a cross and made to wear a crown of thorns on his head, is thrown by the natives into the waterfalls. This prompts the Jesuit priest Gabriel to venture climbing up to the Indians in an attempt to convert them. Arriving exhausted in the jungle above the waterfalls, he takes his oboe out of its case and commences playing. He does not notice that the Indians have surrounded him and are poised to attack, but his music assures them of his peaceful intentions. He succeeds in converting them. Ultimately, a mission is built; however, it gets pulled into the conflict between the Portuguese and the Spanish colonial powers. The slave trader Rodrigo Mendoza joins the struggle—Mendoza had murdered his brother during a fight, and this event is explored in a longer subplot. Mendoza and Gabriel are killed in an unparalleled massacre; with the exception of several children, the Indians are eradicated by soldiers.

Besides the Jesuit priest Gabriel (Jeremy Irons) and Mendoza (Robert De Niro), the principle characters in the film are members of a South American tribe who to this day live under primeval conditions and whose acting was coached by the director through simple instructions. The storyline is supported by the score, which Ennio Morricone tied in with the leitmotif. However, in The Mission, the three most important musical elements support ideas more than they characterize persons.

The director had reckoned that equipping his protagonist, the Jesuit priest Gabriel, with a sounding prop—the oboe—could be translated musically in such a way that it would have become evident to the audience why he was spared the destiny of the murdered missionary shown at the beginning of the film. The oboe melody, the central musical element, is closely aligned with the image. A close-up shot shows the histrionic, in no case very musical, movements of the priest’s fingers playing his oboe while the Indians approach him poised to attack. Morricone was able to remove any musical meaning from these finger movements. As in a ritardando, embellishments are developed that are reminiscent of the baroque practice of ornamentation. In combination with sustained tones, they bring about the emotionally haunting features of a floating melody that is only suggested.

A further element serves to evoke the indigenous people: repetitive, rhythmic echoes from archaic music combined with sounds from a panpipe. Moreover, Morricone conceived a Palestrina-style motet as a third musical element for the newly built mission. Independent from the film and going beyond the accusatory gesture of the director, Morricone wanted to make audible the possibility of the coexistence of the Indians and the conquerors. In order to do so he composed a combination of the three musical elements, which superimposed result in a harmony. The director found room for this powerful music (On Earth as It Is in Heaven) only in the trailer. It is also worth listening to the background noise (remnants of underscoring, in particular during the jungle scenes) woven in with the music in this film. The echo was carefully conceived—for example, an oboe melody with echo is used when the camera sweeps into the distance. It lends the film image depth and also contributes to the semantization of the images through the music.