The Poison Sky (Part II)
Series 4 Episode 5
The Sontarans activate their masterplan, and begin to choke the whole of planet Earth. UNIT is left defenceless, but there's a traitor in their ranks, and as interplanetary war edges closer, the Doctor has to fight to keep both Martha and Donna alive - but will he have to make the ultimate sacrifice?
Trivia
  • Part two of a two-part story.
  • This episode features the second cameo appearance from Rose Tyler. She flickers on the TARDIS monitor and appears to be calling out for the Doctor. It happens so quickly that many fans missed it during the episode's original broadcast. Whatever you do, don't blink!
Memorable Quotes
Doctor Who Series 4, Volume 3 DVD DVD
Doctor Who Series 4, Volume 3

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