It's now 1966, three years after Prem and Kamini's arrival, and they have become very much a part of the Trefelin community. But their lives and those of everyone in the village are about to change when its highflying 'prodigal sons' Basil and Robert Thomas, return to bring a first real taste of the swinging '60s.

Excitement reigns over the Thomas brothers' plan, but not everyone is keen on them. When an act of sabotage breaks the calm of the village, Prem finds himself facing his darkest hour.

Prem, Emlyn and Owen find themselves trapped underground following an unexplained accident at the mine. Basil continues to try and convince the villagers to exchange their deeds for new houses.

Prem and Emlyn find out that foul play is responsible for the collapse at the mine. Aled and Daf are the prime suspects, despite their protests of their innocence. Robert attempts to convince Megan to leave Trefelin with him, and it’s down to Prem to find out the real truth about his past.