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.

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

The village of Trefelin is preparing for the annual summer fete, but there's a lot going on behind the scenes. Dr Sharma is preparing to leave the village for good, and Mrs Sharma goes in search of the missing Dan - but she finds more than she bargained for.

Sharpe has been promoted, and Megan pleads with Dr Sharma to stay and help the miners fight for justice. The series builds to a climax as the doctor takes on Sharpe once and for all...

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

Prem is under a lot of pressure to find and save Dan before it is too late.

Trefelin is deserted as Prem waits for a vaccination unit to arrive from Cardiff. But Reverend Todd is still determined that only he can save the village, and wastes no time in telling the villagers that God has stepped in where Prem's medicine has failed. The community seems oblivious to the deadly outbreak that it faces, and Prem seems to be losing the fight.

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.

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.