WARNING: This episode contains significant spoilers for Season 4 of Miss Scarlet and The Duke. For four seasons, we’ve watched Eliza Scarlet and William Wellington work together to solve a seemingly endless stream of serpentine mysteries in Victorian era London. But by the fourth episode of Season Four, Eliza and William's relationship is forever changed. Stuart Martin, who has played William Wellington for the past four seasons, will not be returning as the Duke for a fifth season. In this episode, we talk with actor Stuart Martin, and writers Rachael New and Ben Edwards about this momentous shift, and what lies ahead for the future of the show.