- Jodie Whittaker (The Doctor)
- Mandip Gill (Yasmin 'Yaz' Khan)
- John Bishop (Dan Lewis)
Episode: The Poison Sky (2)
Air Date: 2008-05-03
Runtime: 47 min
The Sontarans continue their evil plot and begin to "choke" the Earth. The Doctor and Donna, now teamed with Martha have to stop them! Can they save Earth before it's too late?