The tenth and final series of the BBC espionage television series Spooks (known as MI-5 in the United States) began broadcasting on 18 September 2011 on BBC One, and continued until 23 October. It consists of six episodes. The series continues the actions of Section D, a fictional counter-terrorism division of the British Security Service (MI5). In August 2011, Kudos Film and Television, the production company behind Spooks, announced that the tenth series will be its last, as they wanted the show to end "in its prime". In this series, former Russian spy-turned-politician Ilya Gavrik (Jonathan Hyde), Harry Pearce's (Peter Firth) opposite during the Cold War, proposes a strategic partnership between Russia and the United Kingdom. Also with Gavrik is his wife Elena (Alice Krige), with whom Harry had an affair during the 1980s. However, over the course of the series Section D must stop those who intend to sabotage the partnership. As well as Firth, Nicola Walker, Max Brown, Shazad Latif, Simon Russell Beale, Lara Pulver and Geoffrey Streatfeild are included as the main cast. The final episode includes a cameo appearance of Matthew Macfadyen, who headlined the first two years of the show. Ratings for the series generally struggled as it went against Downton Abbey, a highly successful period drama series from ITV1, which was seen by nearly twice the audience; the series attained a per-episode average ratings of 5.41 million viewers. Reviews of the final series were polarised between positive and negative, with critical opinions ranging from "as impressive as ever" to looking "tattered and tired". The DVD box set of the tenth series was released on 28 November 2011 in Region 2, on 6 March 2012 in Region 1, and on 4 April 2012 in Region 4. Cast Main Peter Firth as Harry Pearce Nicola Walker as Ruth Evershed Max Brown as Dimitri Levendis Shazad Latif as Tariq Masood (episodes 1–2) Lara Pulver as Erin Watts Geoffrey Streatfield as Calum Reed Guest Simon Russell Beale as Home Secretary William Towers Jonathan Hyde as Ilya Gavrik Alice Krige as Elena Gavrik Matthew Macfadyen as Tom Quinn (episode 6) Episodes Casting Peter Firth returned as Harry Pearce. The tenth series began with Harry on "gardening leave" after trading Albany, a state secret, for Ruth's safety. Also, Harry recalls an operation during the 1980s where he fell in love with Russian double agent Elena. Firth said that Harry would