The Poison Sky

Episode Guide:
The Poison Sky

Written By:
Helen Raynor

Starring:
David Tennant - Doctor
Catherine Tate - Donna Noble
Freema Agyeman - Martha Jones

Alien:
Sontarans

Air Date:
3rd May 2008

Synopsis:
The Sontarans activate their masterplan and begin to choke the whole of planet Earth, as Russell T Davies’s Bafta Award-winning time-travelling drama continues. UNIT is left defenceless, with 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?