From the rivers of Northern Ireland to the slopes of Spain, Barra Best discovers how passionate individuals across the Europe and the UK are helping species and environments under threat.By the banks of the Ballinderry river, Barra hears how farmers and conservationists are working together to turn the fortunes of a miraculous mollusc around. Freshwater pearl mussels can filter up to fifty litres of water a day, but pearl fishing and pollution means the creature's future is in peril. As he helps release mussels into the river, Barra discovers how coordinated efforts mean the mussel's future in Northern Ireland is looking brighter.In Scotland, cameras follow work as a pre-release enclosure is prepared for wildcat kittens in an effort to ensure Scotland's rarest and most threatened mammal continues to populate the Cairngorms. A farmer in the Netherlands explains how he's ensuring the country's national bird can thrive on his land once more, while in Ireland, discover how a change to the country's motorways has helped save another farmers' friend.On a dusty hillside outside Grenada in Spain, Barra hears how an ancient irrigation system developed over 1,200 years ago could now offer a partial solution to the Costa del Sol's water supply issues.