Charlotte Smith and Matt Baker head to Elan Valley, nestled in the heart of the Cambrian Mountains, where the Welsh natural world is getting ready for the onset of winter. The valley is a patchwork of habitats including Celtic rainforests, open moorland and raging rivers, all dominated by huge dams. These dams have changed the landscape forever, and Charlotte finds out how the rivers of Elan Valley have recently welcomed back migrating salmon. She also helps restore peatlands by getting behind the wheel of some earth moving machinery to rework the topography of the rugged peat landscape. Matt helps drive cattle down into forests on the valley floor to not only provide them with shelter for the winter, but to improve ancient Celtic rainforests. Charlotte looks at how some farmers have started a campaign protesting and blockading supermarket depots to demand fairer prices. Adam travels to the Royal Welsh Showground in Builth Wells where the Winter Fair is in full swing.