the third series, they were "99 per cent sure" Macfadyen would not return until they heard he wanted to come back for two episodes because he did not want to leave the series so soon. Keeley Hawes also returns in the series as Zoe Reynolds. Hawes wanted to leave the series also after the first six episodes. David Oyelowo makes a return as Danny Hunter. After Tom's exit, it allowed Danny's character to develop further. Oyelowo also announced his intention to leave the series, after the finale episode. Peter Firth returns as superior Harry Pearce. After two seasons, Firth attempted to lighten Harry up "a little bit" after his mother suggested the character "smile more," despite the fact that Harry is a serious man. Nicola Walker returns as Ruth Evershed. First appearing in the second series, Walker felt more like the "new girl," but felt more experienced upon her return to the third. Shauna Macdonald also returns as Sam Buxton. The five-month filming gap between series two and three left Macdonald "a bit de-Spookified" as she was more focused on her film career. Hugh Simon and Rory MacGregor return as Malcolm Wynn-Jones and Colin Wells, respectively. When the producers knew Macfadyen would leave, the producers decided to introduce new cast members, one of which was Rupert Penry-Jones as Adam Carter, the new protagonist. Early on in the creation of Adam, the producers had an interest in casting Penry-Jones for the role; however, it took the actor three auditions until the producers finally decided to cast him. Unlike Tom, Adam would have a different character dynamic; he has an MI6 background, and is married. A change from the girlfriend/boyfriend storyline for Tom and Ellie Simm in the first series, the producers noted it is common for secret service officers to be in a relationship with others in the same field of work. This led to the introduction of Fiona Carter, portrayed by Olga Sosnovska. Sosnovska was previously approached to appear in the second series, but was unavailable. She later auditioned for Fiona, and was later told she won the part when she was in New York City. The actress was only given a brief on her character—a ball breaker, ultimate professional, cold and calculated—which did not give her much to work with. Sosnovska initially found Fiona irritating in the fourth episode, but later opened up to the character after her return