With Prem, Emlyn and Owen trapped underground and no-one on the surface aware of their predicament, Robert takes advantage of his brother Emlyn's absence by making a play for Megan. Aled and Daf become the primes suspects after it is discovered that the mine collapse was not an accident. Kamini enlists Dan's help to uncover the real story behind the new town, forcing Basil to reveal his true ambitions. Prem's investigations shine a light on Robert's dark past.