Iolo explores the stunning Dee valley, from wintering birds along the estuary, to displaying black grouse on moorland, rare freshwater-pearl mussels, and spawning sea trout.

Iolo explores the Teifi river valley, and finds a slow worm hunting, meets a coracle fisherman, is thrilled by a fishing Otter, and watches a pair of kestrels at their nest.

Iolo Williams explores the Tywi river valley, from Llansteffan's coastal dunes to fallow deer ruts, ancient oak woodlands and the remote heights of the Tywi forest.

Iolo Williams explores the Usk valley, from Newport's urban wildlife to ground-nesting birds, a huge lesser horseshoe bat roost and scarce firecrests.