Bendor and Jacky visit the the Swansea museum store to uncover a valuable lost masterpiece that will not only become a jewel of Swansea museum’s collection, but also rewrite art history. A giant painting of local coal miners prompts Jacky to re-examine the life of the man who painted them, the renowned Polish artist Josef Herman.

Haddo House in Aberdeenshire may house some of Scotland's greatest lost paintings.

Bendor and Jacky investigate what have long been disregarded as low-value copies of works by Flemish artist, Peter Breughel the Younger, at the Ulster Museum. They also visit the Northern Ireland Assembly at Stormont-in which a controversial painting once slashed with a knife is now kept in a room away from public view.

Pollok House, a country house owned by Glasgow City Council and looked after by the National Trust for Scotland, holds a collection of Spanish art --- the legacy of William Stirling-Maxwell.

Joseph Wright of Derby was an acclaimed English artist inspired by the Industrial Revolution, and Derby Museum has the best collection of his paintings in the world. Grosvenor and Dabiri peel back the layers of a modern restoration on a landscape painting in the museum's vaults to determine if it is a hidden masterpiece.

Grosvenor and Dabiri head to Carmarthenshire to investigate two intriguing portraits of a local nobleman and his wife, the Earl and Countess of Carbery, possibly painted by the great Sir Peter Lely in the 17th century. However, Bendor has a hunch that the portrait of the Countess was done by Mary Beale, Britain's first commercially successful female artist.