Ross prepares for his trial as Demelza and Elizabeth try to help his cause. George does everything in his power to harm Ross, Francis wrestles with his conscience, and Dwight clashes with an entitled heiress, Caroline Penvenen.

Ross and Demelza face financial ruin, and George plans revenge on Jud. Francis, meanwhile, tries to rebuild his life and extends an invitation to Ross and Demelza.

Needing money to open a mine free of George's influence, Ross strikes a deal with a local smuggler. Dwight, meanwhile, tries to diagnose an epidemic and receives help from an anonymous benefactor.

An informant in the smuggling ring poses a serious threat to all, and George buys Ross's debt to finally crush him. Meanwhile, Caroline returns to Cornwall to make an announcement, but it is Elizabeth who reveals a great secret.

Ross tries to help Francis's family financially, but George calls in Ross's debt. Demelza toils loyally to protect all at Nampara, and Dwight and Caroline continue to meet in secret.

Ross joins a smuggling trip in the Isles of Scilly in order to meet Mark Daniel but, in his absence, George moves in on Elizabeth. Caroline convinces Dwight they must elope for a new life in Bath, and Captain McNeil plans to ambush the smugglers on their return.

Ross and Dwight stand trial for their part in the smuggling. A new tin lode gives Ross renewed hope in Wheal Grace, but it is George who is there for Elizabeth when her mother falls ill and deals Ross a bitter blow.

Ross closes Wheal Grace for good. With Elizabeth wrestling with a life-changing decision, Demelza's world has been turned upside down. How will harmony be restored?

Dwight enlists in the navy to forget Caroline, and Demelza visits Verity to spend some time apart from Ross. While Ross considers rejoining his regiment, Elizabeth and George settle into married life, but George's plans provoke the locals to riot.