Alan Titchmarsh, with celebrity experts and enthusiasts, reveals the hidden treasures to be found at Britain's historic houses and estates. Alan visits Quarry Bank Mill in Cheshire, an 18th-century cotton mill that is still home to a working mill as well as a museum. Oz Clarke uncovers some Civil War history at Dunster Castle in Somerset. Jon Culshaw visits a stately pile in an unusual location, Dan Jones joins an architectural dig on the south coast, and Clive Aslet visits the spectacular grounds of Biddulph Grange in Staffordshire.

Alan Titchmarsh reveals the secrets of the Cistercian monks who lived at Fountain's Abbey in North Yorkshire over 800 years ago, and visits its neighbour - the spectacular Studley Royal Water Garden. Anneka Rice is at Mottisfont in Hampshire and Britain's last working water-driven spade mill. Miriam O'Reilly joins a bat watch on the South Downs, and Dan Jones treads in the footprints of Giants in County Antrim.