Viv Rook becomes prime minister, and while Edith investigates mysterious rumours, Rosie finds herself trapped in the system.

Cast: Emma Thompson, Rory Kinnear, Ruth Madeley, Maxim Baldry, Jessica Hynes, T'Nia Miller, Anne Reid, Lydia West, Dino Fetscher, Kieran O'Brien, Emma Fielding, Sharon Duncan-Brewster, Adrianna Bertola, Jade Alleyne, Rachel Logan