The Poison Sky (TV story)

"The planet's going nuclear!"

- Staal

Synopsis
The Sontarans activate their masterplan, and begin to choke the whole of planet Earth. UNIT is left defenceless, with a traitor in their ranks. And as interplanetary war edges closer, Doctor has to fight to keep both Martha and Donna alive - but will he have to make the ultimate sacrifice?

Plot
To be added

Cast

 * The Doctor - David Tennant
 * Donna Noble - Catherine Tate
 * Martha Jones - Freema Agyeman
 * Wilfred Mott - Bernard Cribbins
 * Sylvia Noble - Jacqueline King
 * General Staal - Christopher Ryan
 * Commander Skorr - Dan Starkey
 * Colonel Mace - Rupert Holliday Evans
 * Luke Rattigan - Ryan Sampson
 * Ross Jenkins - Christian Cooke
 * Private Harris - Clive Standen
 * Private Gray - Wesley Theobald
 * Newsreader - Kirsty Wark

Production crew
To be added

Story notes

 * Helen Raynor wrote this episode. Her Series 3 episodes Daleks in Manhattan and Evolution of the Daleks both occupied fourth and fith episode in the series. This two part episode also occupies episode four and five.
 * This is part two of a two part story that began with The Sontaran Strategem.
 * This two parter is Douglas Mackinnon's first story as director.

Ratings
To be added

Myths
to be added

Rumours

 * Sylvia gets an axe and breaks Wilf out of the car
 * The Sontaran's copper exitation will be deactivated. This is likely as many Sontarans are seen shot in the trailer including Skorr.
 * The Sontarans need the gas from the cars to make the earth habitable for themselves.
 * A Rutan army will appear in flashback.
 * Details of the Brigadier's whereabouts are revealed. This seems very likely as in the edited Fear Forecast one of the children reacts to a character that was with a previous Doctor. Given UNIT's presence, this could well be Lethbridge Stewart
 * The Sontarans steal the TARDIS. Also likely, as again in the Fear Forecast it is mentioned something happens to the TARDIS
 * UNIT will launch a nuclear strike. This is highly likely as the trailer for this episode is set around a countdown at one of UNIT's bases. Also during the trailer Staal states that: "the planet is going nuclear".
 * Donna will kill a Sontaran by the Probic Vent.She is mentioned as trying to get at a probic vent by the Fear Forecasters 
 * The Doctor's hand will reappear. This seems likely as the Fear Forecast also mentions something familar on the TARDIS floor
 * The TARDIS will take off with the Doctor, Donna and Martha stuck inside at the end of the episode.

Filming locations
To be added

Continuity

 * The Valiant last appeared in DW: Last of the Time Lords.
 * The Doctor wears a gas mask and asks "Are you my mummy?" like the Empty Child in Albion Hospital (DW: The Empty Child/The Doctor Dances)

Discontinuity, Plot Holes, Errors

 * A corridor explodes with Sontarans inside it. This is the same corridor that exploded in the Torchwood episode Sleeper. This is not a plot hole or error. It is common for TV shows to make use of sets more than once to save on the budget

DVD and other releases

 * It will be released on the Series 4 boxset DVD in November 2008.