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.

With Trefelin under quarantine, supplies are getting low. Despite Prem's attempts to piece together the evidence, the real source of the outbreak is still unknown. As one by one the miners who played cards in Ceri's barn fall victim to the virus, it seems that Dan knows more than he is letting on about how he fell ill.

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.

Reporters gather at the surgery to hear that the outbreak of smallpox in Trefelin is finally under control. But Prem is not convinced that they have managed to locate the real source of the disease, and so the village is still not safe.

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.

The sleepy Welsh mining village of Trefelin is in for a shock. When the local doctor dies, his replacement isn't quite what people expect - Prem Sharma is the Indian doctor.

Colliery manager Richard Sharpe is still desperate to find a mysterious green leather diary left behind by Prem's predecessor, Dr Elwyn.

The Indian Doctor's wife, Kamini Sharma, is still desperate to leave the village of Trefelin. But as she tries to escape, she finds herself becoming the only person who can help local tearaway Dan when he gets into trouble.

Prem Sharma and his wife Kamini await the arrival of his formidable mother-in-law, Pushpa who is paying a visit.

The new doctor, Prem Sharma, comes up with a cunning plan to diagnose the miners' health problems.