Barra Best makes a journey across the 4,000 square kilometres of the Foyle river network, criss-crossing his way across the many rivers and streams that make up its great catchment. He follows its route across three counties - Donegal, Tyrone and Londonderry - to Lough Foyle.

It’s an early start as Barra finds out the mystery of Beaghmore, thought to be Ireland’s largest single collection of stone circles. He visits the place officially designated Northern Ireland’s darkest place at Davagh Forest and gets a sneak preview of the brand new OM Observatory on the site. He joins a woman whose hobby is photographing old and abandoned buildings to try and uncover the secrets behind a house in the Sperrins. Then there’s some fun whitewater rafting on the River Strule before meeting up with a group of amateur film stars in Castlederg. Show less