Rumours spread of a scandalous relationship between Ross and Demelza.

Demelza gives birth. Ross welcomes old friend Dr Dwight Enys to Cornwall.

Sam and Drake provoke Trentishoe and Ross's stubbornness gives George the upper hand. Meanwhile, a great naval battle leaves Dwight's fate in question.

Ross is ordered to leave Roscoff under threat of execution. He travels with Tholly to meet his contact in France, but finds information about Dwight's fate comes at a high price. Sam leads a congregation of methodists in protest outside the church - only to face broken promises from George, who revokes their lease on the meeting house, which leads them to turn to Elizabeth for help. Geoffrey Charles has some words of advice for Drake, who has shared a moment of intimacy on the beach with Morwenna.

George proves merciless as the new magistrate, and Clowance is christened. Ross discovers the means to both help Dwight and combat Cornwall's famine.

The Poldarks determine to get their relationship on track and the Enyses announce they're expecting a baby. Hugh's worsening health threatens his chance to stand in the election, and the prospect of him remaining in Cornwall adds pressure to the Poldarks' fragile marriage. At the Sawle Feast, Tom Harry challenges Sam to a wrestling match. When Emma offers herself as the prize, Sam accepts.

Ross Poldark returns home after American Revolutionary War and rebuilds his life with a new business venture, making new enemies and finding a new love where he least expects it.