Continuing from where “The Poison Sky” left off, the TARDIS kidnaps the Doctor and his companions Donna Noble and Martha Jones; and whisks them away to the planet Messaline, in the midst of a generations-long war between humans and the Hath, fish-like humanoids. Emerging from the TARDIS; Martha reveals that although she wanted to be home, she did miss the adventure. They are then met by armed men working for General Cobb. Cline, the leader of the men, forces the Doctor’s hand in a progenation machine, using his DNA to create a soldier — Jenny, the episode’s titular character.
The Gallifrey Guardian 
