Art experts Jacky Klein and Dr Bendor Grosvenor visit our most diverse and fascinating museums as they track down previously unknown paintings by some of the world's great artists. Haddo House is one of Britain's most northerly stately homes. Tucked away in the wilds of Aberdeenshire, it has been home to prime ministers and earls - but is it also home to some of Scotland's greatest lost paintings? Nearby, in the storerooms of the Montrose Museum lies a mystery painting with a giant hole in it.