Weatherman Derek Brockway visits Rhondda Cynon Taf for a seven mile circular trail that starts and ends in Hirwaun. On his route he learns about the area's industrial past; visits a whisky distillery and takes a ride on the world's fastest seated zipline. Meanwhile wildlife expert Lizzie Daly investigates how otters are under threat and Onkar Singh Purewal goes on a trek with alpacas across the Brecon Beacons. MEDIUM: Weatherman Derek Brockway visits Hirwaun in Rhondda Cynon Taf to learn about the town's industrial heritage.