"The Poison Sky" (which first broadcast on May 3, 2008) was directed by Douglas Mackinnon, produced by Susie Liggat and written by Helen Raynor (a British television screenwriter and script editor, best known for her work on the relaunched BBC science fiction series Doctor Who).
"The Poison Sky" is the fifth episode of the fourth series of British science fiction television series Doctor Who. It was broadcast on BBC One on 3 May 2008. Douglas Mackinnon Susie Liggat Helen Raynor Helen Raynor (born March 1972) is a British television screenwriter and script editor, best known for her work on the relaunched BBC science fiction series Doctor Who. 
