South African writer Damon Galgut has now been shortlisted for the Booker three times, and the latest is for his ninth book, The Promise. It is a family saga that begins in 1986 apartheid South Africa and follows one Afrikaner family through to the present. At its heart, is a broken promise that serves as an allegory for modern South Africa. But as Damon tells Sarah L'Estrange, it's also about a dysfunctional family.