Secret cameras capture the spectacular beauty of Dalby and Cropton Forests on the edge of the North York Moors, and the incredible species of wildlife that inhabit them. In the first episode, cameras follow a family of beavers that were established in Cropton in 2019 as part of a scientific trial to see how they would change the landscape. Elsewhere in the forest, Britain's only venomous snake, the adder, soaks up the heat of the summer sun, and a team of bird conservationists are on the lookout for nightjars.