It's over 150 years since climbing developed as a sport and in that time Britain's great crags have been thoroughly explored. In their search for bold new routes, two of Scotland's best rock athletes, Dave MacLeod and Alan Cassidy, travel south of the Border to the heart of the English climbing scene. In an astonishing week, they attempt two innovative first ascents - one deep underground and the other in a huge cavern. This film follows them as they inch their way from darkness into light.