S1, E5: Series in which Griff Rhys Jones explores some of the most beautiful and enchanting parts of Wales. Griff wakes up in a tree house in the middle of an ancient wood and discovers that his challenge this time is to find the Holy Grail! In a land of myth, mystery and hidden treasures he tries his hand at panning for gold before meeting a modern myth maker who runs an old cinema. In Aberdyfi at the mouth of the River Dyfi, Griff begins to unravel the legend of Cantre'r Gwaelod - the Welsh Atlantis that reputedly lay in the Bay of Cardigan. The discovery of a petrified forest only stimulates his interest, but it is in Aberystwyth that Griff finally learns about the legend of the Holy Grail of Nanteos.