Host David Maybury-Lewis revisits the Xavante of Brazil to see how they have changed since 1959, and then journeys into the Peruvian Amazon to unravel the mystery of the Mashco-Piro, a tribe that has chosen to remain hidden from the outside world. Only by understanding "the Other" can we get a proper sense of our own place in the world. Our contact with tribal societies will change them forever - but can it also change us?