Masterpiece: Poldark, the rip-roaring TV drama called “swoon-worthy” by the Los Angeles Times returns for a fourth season of action-packed episodes, starring Aidan Turner as the roguish Ross Poldark and Eleanor Tomlinson as his fiery partner, Demelza. In Season 4, it’s 1796, and to defend Cornwall and those he loves from an empowered George, Ross must play the political game on a journey that takes him to the nation’s capital and into new perils.