Iolo Williams tracks wildlife in one of Wales' extraordinary landscapes - the Cambrian Mountains. These hills are home to some of Wales’ best wildlife and Iolo’s task is to track it down – can he find Wales’ only golden eagle, or see an osprey actually catching a fish or capture a pine marten on camera? These remote uplands form the heart and spine of Wales. It's an area where the mighty rivers Rheidol, Ystwyth, Teifi, Tywi, Wye and Severn all have their sources; and is the least populated area of Wales. This is also Wales' lakeland as it has so many reservoirs including those in the Elan Valley. With a handful of roads crossing this stunning area of mid Wales, much of the landscape is only accessible on foot. It's a place where you can walk for miles without seeing a soul, but when you do find wildlife, it's always special. Iolo's first target is Wales' rarest and most elusive mammal, the pine marten, and he finds one at night lurking in a conifer forest. Iolo also looks for ospreys fishing on Llyn Clywedog. It's a magnificent bird of prey that's only relatively recently returned to nest in Wales after being extinct for centuries.

Iolo Williams tracks wildlife in one of Wales' extraordinary landscapes - the Cambrian Mountains. In this episode Iolo heads for the Elan Valley to look for cuckoos. They're easy to hear, but not so easy to see. He also finds red squirrels that are genetically unique to the Cambrians in a remote conifer plantation. And he looks for golden plover, one of the rarest breeding birds in Wales, on the hills surrounding Plynlimon.

Iolo Williams tracks wildlife in one of Wales' extraordinary landscapes - the Cambrian Mountains. In this episode Iolo heads to the Tywi forest to look for goshawks. They're big formidable birds of prey and became extinct in Wales by the end of the 19th century, but since the 1960s they have gradually re-colonised the Cambrian forests. Iolo tracks them during the late part of the nesting season and finds fully grown chicks in a huge nest with bits of eaten prey below. Iolo also explores the Elan Valley to find one of Wales' most critically endangered bird species, the curlew, as they attempt to breed on rough ground near the reservoirs. And he discovers a stunning day-flying moth called the Welsh Clearwing. It's so rare that it can only be found in a handful of places in Britain and its stronghold is in the Cambrian Mountains.

Iolo Williams tracks wildlife in one of Wales' extraordinary landscapes - the Cambrian Mountains. In his final trek of the series Iolo looks for a golden eagle. It's a bird you wouldn't expect to see in Wales as it became extinct there over 400 years ago. But an escaped golden eagle has been secretly living in the Cambrian Mountains for nearly ten years. Iolo scours woodlands and the Cambrian hills to find this magnificent bird of prey. It's a bird with a seven-foot wingspan, making it nearly three times the size of a buzzard or a red kite. So you would think that it’s easy to find, but the eagle has a huge flying range and doesn't seem to want to be found.