波尔达克 第四季是一部剧情/历史/爱情片，Ross (Turner) must defend Cornwall from an empowered George Warleggan (Jack Farthing), and risks everything he holds dear as he embarks on a political journey which takes him to the nation's capital. Demelza (Tomlinson) finds her loyalties torn, Elizabeth (Heida Reed) tries to strengthen her marriage, Morwenna (Ellise Chappell) continues to be oppressed by husband Reverend Ossie Whitworth (Christian Brassington), and the Enyses (Luke Norris and Gabriella Wilde) are tested as never before.
Times are hard for the locals as grain is being sold to the highest bidders abroad. A corn riot breaks out in Truro, and the Carne boys, innocent bystanders, are among those arrested. MP George Warleggan manipulates the trial against them, but Ross does his best to save them, impressing Sir Francis Basset, who wants him to stand in the upcoming election. Demelza is torn between her admirer, Hugh Armitage and Ross, but she and Ross look to rebuild their marriage. Caroline has good news for Dwight, while Morwenna continues to endure life with her husband.