Cyfres yr Hambons: Dirgelwch y Defaid

Who can solve the mystery of the missing sheep? Sheep are going missing from the fields - and no-one knows how or why. As the local farmers all disagree with each other about how to deal with this problem, three friends - Llew, Ianto ac Efa - decide to investigate the matter themselves. What is happening to the sheep? Are they being stolen by thieves? Or are they being swallowed up by the earth?