Isabel Hilton and guests discuss Walter Salles's new film. Behind the Sun is set in the Brazilian badlands during 1910 and tells the story ofTonho. Ordered by his fatherto avenge the death of his older brother, he knows that to obey will result in his own death. Faced by an ever-increasing spiral of violence he is torn between fulfilling his ancestral duty and rebelling against it. Plus a critical look at the early output of BBC4, the new cultural digital TV channel.