University Challenge icons and real-life best friends Eric Monkman and Bobby Seagull are on a road trip with a difference. Feeding their insatiable appetite for knowledge, they visit Scotland, England, Northern Ireland and Wales in search of hidden gems of British scientific and technological ingenuity. Along the way, everything they touch turns to knowledge. This second episode, their 'genius guide' to Wales, has a strong industrial engineering flavour. Monkman and Seagull begin by sailing across the highest navigable aqueduct in the world - Pontcysyllte Aqueduct. Designed by Thomas Telford and completed in 1805, this pioneering piece of engineering was built to carry raw materials over a vast ravine into England during the industrial revolution. The tiny village of Hawarden gives the brainy duo the opportunity to stay overnight in the UK's only residential library, surrounded by former Prime Minister William Gladstone's unique collection of books. Approaching Mount Snowdon, they visit a former quarry hospital in Llanberis, now a museum highlighting its previous life caring for injured slate quarry workers. Here they use their vast knowledge to work out what some of the old medical apparatus was used for. Eric and Bobby also seek some last minute mountaineering inspiration from Edmund Hillary and Tenzing Norgay, by visiting the hotel they stayed at while training on Snowdon for their pioneering ascent of Everest. Finally, the two friends make an attempt on the summit of Mount Snowdon itself - via the mountain's iconic rack-and-pinion narrow gauge steam railway train, which has been ferrying tourists to the top of the peak since 1896.