The Mission is based on a true story of Jesuit priests trying to save South American Indians from enslavement. The director is Roland Joffe. It stars Robert De Niro (I've seen him in Brazil), Jeremy Irons, Liam Nissan (I've seen him in Excalibur, Star Wars: The Phantom Menace and Batman Begins). This film is #15 on the Arts and Faith list of top 100 spiritually significant films. It won the Palme d'Or at the Cannes Film Festival in 1986.
The Younger Son found it slow-moving but liked it anyway, though he said he wouldn't want to see it again for a while. I thought it was beautiful, both visually and the music. It's been years since I saw it last, but I found it fascinating both times.