S1, E1: Bhutan, the beautiful land-locked nation in the Eastern Himalayas, has always been steeped in mystery. In this revealing BBC travel documentary, Absolutely Fabulous star Joanna Lumley retraces the steps her grandparents took in the country 60 years before. Through her eyes, a world which challenges accepted ideas of wealth and happiness is explored. But what family secrets will Joanna uncover?