An idyllic British river: misty dawns, dancing mayflies, lazy trout and fluffy chicks paddling under the watchful gaze of their parents. "My Halcyon River" is an intimate portrait of a secret world where otters hunt on the midnight current, mink lie in wait to ambush unwary victims and gleaming kingfishers pierce the water to spear their prey. These dramas, both mortal and touching are revealed through the eyes of a man who has loved the river since he was a boy, cameraman Charlie Hamilton-James.

Filmmakers Charlie Hamilton-James and Philippa Forrester went in search of otters on a short stretch of the River Torridge in Devon, immortalised 80 years ago by Henry Williamson in his famous novel Tarka the Otter. Over months of patient fieldwork they got to know and film a family of wild otters. The result is both a lyrical portrait of these shy creatures and a tribute to Williamson's skills as a writer and naturalist.