page_title: The Sontaran Stratagem
section_title: Production
hierarchical_section_title: The Sontaran Stratagem / Production
caption_attribution_description: English: Actress Freema Agyeman at the launch of Series 3
context_page_description: "The Sontaran Stratagem" is the fourth episode of the fourth series of the British science fiction television series Doctor Who, which depicts the adventures of a time-travelling humanoid alien known as The Doctor. The episode was broadcast on BBC One on 26 April 2008. The episode and its sequel, "The Poison Sky", were written by Helen Raynor, who previously wrote the linked episodes "Daleks in Manhattan" and "Evolution of the Daleks" in the third series.
  "The Sontaran Stratagem" features the first appearance of the alien Sontarans to the series since the 1985 Colin Baker story The Two Doctors, as well as former companion Martha Jones, last seen in "Last of the Time Lords." The episode takes place on present-day Earth, where Martha and UNIT summon the Doctor for assistance concerning ATMOS, a revolutionary piece of green technology installed in 400 million cars worldwide. ATMOS is later revealed to be part of a Sontaran plot to poison the atmosphere.
  Show runner Russell T Davies had considered making the Sontarans return since the revival of the series and wanted to show changes in Martha's personality after her departure.
caption: The episode sees the return of Freema Agyeman as Martha Jones.
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