Series 4 (2008)
Episode title: The Doctor's DaughterFeaturing: Tenth Doctor
Companions: Donna Noble, Martha Jones
First shown: 10th May 2008
Related articles: The Hath
Guide: This episode continues from where episode 5 (The Poison Sky) left off, with the Doctor, Donna and Martha being transported in the TARDIS unwillingly.
They land on the planet Messaline, a planet torn apart by generations of fighting between the humans and the Hath, fish like humanoids. When the Doctor and co. leave the TARDIS, they are captured by the humans, who forces the Doctor to put his hand in a progenation machine, which takes a sample of his DNA from his hand, and produce an adult soldier for the war. This adult soldier is called Jenny, and is the Doctor's Daughter.
But the Doctor refuses to accept that she is his daughter until the end of the episode. The Hath come and fight the humans, who cause an explosion which brings part of the tunnel down, with the Doctor and Donna on the human side, and Martha on the Hath side.
The Doctor and Donna are taken captive, and Jenny is also imprisoned because she came from the Doctor. Donna notices numbers on the door, and writes them down. Jenny helps the Doctor and Donna escape, and they go off to find the 'Source' which the humans and Hath have been fighting for.
The Hath, also finding the way like the humans, also go after the 'Source' with Martha. Donna keeps writing down the numbers she sees, and notes that they are decreasing. When the Doctor, Donna and Jenny get to the control centre of the ship that brought the humans and Hath to the planet Messaline, they discover that the captain died, only 7 days ago.
Donna tells the Doctor about the numbers, and she realises that they're completion dates for each section built, going over 7 days. The Doctor then realises what was meant by a generations old war - each generation didn't last long because of the progenation machine, so although it had only been 7 days, it could have been 5 generations or more!
The Doctor and Martha meet up again, and all four of them go off and find the 'Source' - a terraforming device designed to make the planet habitable for both humans and Hath. The Doctor smashes it, hoping it will bring peace to both races, but General Cobb, from the human side, liked war, and shoots the Doctor, but Jenny gets in the way of the bullet and is killed.
The Doctor then takes Cobb's gun, which has been knocked out of his hand when other humans restrained him, and he points the barrel at Cobb's head for many seconds, before dropped it and saying "I never would" and "Build this society on that! A man that never would!"
The episode ends with the Doctor taking Martha back home and him and Donna continuing their adventure, before going back to Jenny who lies dead on a table, suddenly blowing the same gold stuff out of her mouth as the Doctor did when he regenerated in the 2005 Christmas special (The Christmas Invasion). Jenny then steals a ship and flies off.