Muddy roads, rusted cars, makeshift shelters and piles of garbage: The desolate images at the beginning of German director Milo Rau’s new film, The New Gospel, show how farm workers live near the southern Italian city of Matera. Most of them are African refugees. They have no residence permit and work for hours under the scorching sun or in the freezing cold for a pittance in the tomato fields and orange plantations. They are hired and supervised by Italian foremen, the “caporali.” The mafia controls the agricultural economy in the Matera region; there is no way around their contact men....