Wales in the 19th Century. Becca is married to Dai, who is transported to the penal colony of Diemen's Land (Tasmania) for rebellion. His brother Gwylim, who is a minister, travels after him by signing on as a ship's chaplain on a ship. He and Becca pretend to be husband and wife so she can come along. The pastor and his sister-in-law start a relationship.

The story was inspired by the stay-down strikers in the 1930s who refused to leave the mines for three weeks. Ernie Bailey, one of the miners, relayed the story to director Karl Francis, but declined appearing in the film because HTV would not pay him on a scale comparable to Tom Jones. Mr. Bailey smoked to his dying day at the age of 99: always a staunch socialist.