Colin and Lucy begin their week-long adventure around the UK's very own wildernesses with a look at our rivers.
Colin travels up the River Wye following the king of fish, the salmon - whilst Lucy discovers the wilder side of canals at night. The show goes behind the scenes with Steve Backshall and the Wild Alaska Live team as they try to film the elusive salmon shark.
Plus viewers will discover how the return of one of Britain's long-lost beasts - the beaver - is changing the landscape and reveal how the UK's rivers are important for one of the world's most peculiar fish – the sea lamprey.