Television broadcaster and keen fisherman Jeremy Paxman travels along four of the United Kingdom's most important rivers. During his trips to the Tweed, the Mersey, the Severn and the Thames, Paxman explores the histories of the waterways and takes part in a number of activities, including a punting regatta on the Thames and a swim with the `Mersey Mermaids'. The natural beauty and wildlife of the respective rivers is captured on screen, and Paxman also talks to a number of people whose lives and professional careers revolve around these geographical marvels.