In 1988, Paul Eastwood and his climbing partner became the first men to free-climb Britain's deepest open cave shaft, rising from within the UK's largest underground chamber and traversing around its highest unbroken waterfall, three times the height of Niagara falls. The iconic route will have gone unrepeated for almost 40 years. Decades later a new team of climbers, Olympian Molly Thompson-Smith and legend Steve McClure, will tackle the climb once again, hoping to join the few who have ever free-climbed the route.