Following the phenomenal success of Halcyon River Diaries in the summer, Charlie, Philippa and the boys are back this festive season with a wonderfully charming and often humorous one-off special. A year has passed, and we join Charlie as he tracks his beloved otters with Gus, sets up an experiment with Fred to see how fast kingfishers actually fly, and tries to record the elusive winter song of a dipper. Philippa is busy re-homing twelve battery hens and making bird cakes with Arthur, until one day a predator strikes and her water vole colony are under threat - could the mink be back on the river?