1702. William III is on the throne and England is on the verge of war. Princess Anne is soon to become Queen, and her advisors vie for influence over the future monarch.
Sarah, Duchess of Marlborough, a close friend with whom Anne has an intensely personal relationship, begins to exert increasing pressure as she pursues her own designs on power. Contending with deceit and blackmail, Anne must decide where her allegiances lie, and whether to sacrifice her closest relationships for the sake of the country.