Martha's sister Tish is working for the elderly Professor Richard Lazarus, a man who claims he will change what it is to be human. The Doctor can't let a comment like that go without investigation and he and Martha set off to meet her family at the reception where the Professor is to reveal all to the world.
The Professor's experiment is to rejuvenate himself, and at first it appears he has been successful, emerging from the manipulator as a much younger man. However, the process has caused his DNA to become unstable and before long he begins to mutate into a monstrous prehensile creature and goes on the rampage, draining the life energy from guests at the event. The Doctor and Martha manage to fight back against the creature and believe that Lazarus is now dead. However he has survived and escapes, and the Doctor, Martha and Tish track him down to Southwark Cathedral for a terrifying final showdown.
Meanwhile a mysterious man has been giving information to Francine about how dangerous the Doctor is, information that has come from none other than Harold Saxon himself.
Filming locations for the episode included Cardiff Museum, the Welsh Assembly's Senedd building and Wells Cathedral.
- - Last of the Time Lords (2007) TV episode, Played by Gugu Mbatha-Raw
- - The Sound of Drums (2007) TV episode, Played by Gugu Mbatha-Raw
- - The Lazarus Experiment (2007) TV episode, Played by Gugu Mbatha-Raw
- - Smith and Jones (2007) TV episode, Played by Gugu Mbatha-Raw
Episodes: 301, 306, 312, 313
Character Profile: Sister of Martha and Leo Jones. She is a PA and finds herself working for Doctor Lazarus and Harold Saxon.