Countryfile heads to the north Cornwall coast. Matt Baker explores its secret glens and historic ruins on a quest to find out about Cornwall's ancient mythological past. James Wong meets the volunteer cliff rescuers looking after us and our best friends. Meanwhile, Julia is on a farm in East Sussex which has a holistic approach to agriculture. Tom Heap is at the other end of the country on the Orkney Islands, finding out whether tidal power could satisfy our need for new forms of renewable energy. Down on the farm, Adam has got his hands full rounding up all his lambs ready for market.