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.

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?

Ross is reunited with his family at home, but tragedy strikes in Cornwall. Dwight tells Caroline some devastating news about Sarah. Ossie is seen visiting Rowella by her husband Arthur, who grows suspicious. Emma returns to give Sam her answer, whilst Drake is persuaded into courting Rosina.

Joining the Enyses and Ross in London Demelza enjoys the city life and accompanies Ross to a charity ball thrown by Warleggan to celebrate his wife's pregnancy. Here she attracts Adderley's predatory attention, leading him to challenge Ross to a duel, the outcome of which makes Warleggan even more anxious to crush Ross. Whilst Demelza, overwhelmed by events, returns to Cornwall, Morwenna has a message for Drake and Geoffrey Charles makes an observation.

As George expands his power through a shady alliance, the Poldarks become caught in a deadly web.

Ross's tenacity in helping Ned bears fruit, but not without cost. Hanson’s presence in Cornwall raises suspicion and as Demelza wrestles with how best to equip the community to look after itself, Morwenna lends herself to the cause and finds new hope.

Ralph seeks to ruin Ned as rebellion stirs and the Poldarks are trapped in the middle.

George’s cabal moves to ruin the Poldarks, and Morwenna wrestles with a heavy decision.

Ross fights for Ned’s life as Demelza uncovers betrayal and the young lovers take flight for a future together.

Ross discovers a French plot, and George finds himself at the mercy of Joseph and Ralph.

With the fate of his nation in the balance, Ross must gamble everything to protect his country and those he loves.

After it is revealed that Nathaniel Pearce embezzled Pascoe’s client’s funds, the Warleggans take action. In London, Ross finds Geoffrey Charles led astray by Adderley. Sam convinces Drake to return from exile following his abandonment of Rosina and Morwenna’s subsequent rejection and Morwenna reveals some news. Dwight meanwhile helps in the development of Truro’s infirmary.

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.

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.

As the election leads to rioting, Elizabeth goes to Bodmin herself. Demelza tries to influence the case by making a personal appeal to the judge, but George has a number of tricks up his sleeve as the day of the trial arrives.

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.

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.

Rumours spread of a scandalous relationship between Ross and Demelza.

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.

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 is adamant George will lose in the election and determines to get a headstone made for Agatha's grave, something Trenwith has neglected. George, meanwhile, questions Dwight over Valentine's legitimacy and - paranoid and jealous - shuts himself to Elizabeth, as Rowella begins to seduce Osborne Whitworth and Demelza receives tokens of Hugh's affection. Sam continues to pine after Emma, as Dwight instructs Osborne to forego intercourse with Morwenna and Cary informs Lord Falmouth that the Warleggans will be opposing Falmouth in the election. Ross returns from his mine to discover Hugh Armitage at Nampara with Demelza - and this time Hugh's attention does not go unnoticed..

The Poldark family finds itself challenged on all fronts and threatened as never before.