Ross Poldark, a survivor of the American War of Independence, travelling home to Cornwall discovers his father has died; calls at his Uncle's home to discover his inheritance in ruins and his sweetheart Elizabeth betrothed to another man, his cousin Francis Poldark. Hostilities among the locals rise when he takes on a kitchen maid, Demelza Carne, beaten by her father who wants her back and with no help from his Uncle who wants him to leave Cornwall; Ross becomes more determined to stay and work his inheritence.

Ross resolves to reopen his family mine with Francis. Demelza struggles to fit in at Nampara, and Verity makes an unsuitable match, leading to a feud between Ross and Charles which ends in a violent showdown.

Ross celebrates the opening of Wheal Leisure as rumours spread of a scandalous relationship between him and Demelza. Francis and Elizabeth celebrate the birth of their new son. Ross must fight to save his friend Jim, sparring in court with Reverend Halse.

News of Ross and Demelza's marriage spreads through the community, damaging Wheal Leisure's prospects. Demelza is filled with anxiety when Francis and Elizabeth invite the newlyweds to spend Christmas at Trenwith.

Demelza gives birth and resolves to help Verity reconcile with Captain Blamey. Ross welcomes old friend Dr Dwight Enys to Cornwall, and Francis's persistent gambling threatens the security of all he holds dear.

With Jim gravely ill in Bodmin jail, Ross and Dwight launch a desperate mission to save him. Demelza is excited to attend a grand ball held by George, who is determined to ruin Ross and his smelting company.