Doctor: David Tennant (Tenth Doctor)
Companion: Freema Agyeman (Martha Jones)
Others
Jessica Hynes – Joan Redfern
Harry Lloyd – Jeremy Baines
Thomas Sangster – Tim Latimer
Tom Palmer – Hutchinson
Pip Torrens – Rocastle
Rebekah Staton – Jenny
Gerard Horan – Mr. Clark
Lauren Wilson – Lucy Cartwright
Matthew White – Phillips
Derek Smith – Doorman
Peter Bourke – Mr. Chambers
Production
Directed by Charles Palmer
Written by Paul Cornell
Script editor Lindsey Alford
Produced by Susie Liggat
Executive producer(s) Russell T Davies
Julie Gardner
Phil Collinson
Incidental music composer Murray Gold
Production code 3.8
Series Series 3
Length 1st of 2-part story, 45 minutes
Originally broadcast 26 May 2007
The Doctor and Martha run to the TARDIS as an unseen enemy fires at them. The Doctor tells Martha that they are being pursued by the Family of Blood, who seek the Doctor's Time Lord life force to prevent themselves from dying. He tells Martha that he must transform into a human to escape the Family's detection until they die out, and gives her a list of instructions to follow. He uses a device called the "chameleon arch" to turn him into a human and transfer his Time Lord essence and memories into a fob watch that he asks Martha to guard.
They land on Earth in 1913. The Doctor takes the persona of John Smith, a teacher at Farringham School for boys, and Martha acts as a maid at the school. John is quiet and timid, but faint memories of the Doctor slip through in his dreams. He catalogues the dreams in a book he has titled A Journal of Impossible Things. John keeps the fob watch on his mantle, but a perception filter around it keeps him from being curious about it. John has also become infatuated with the school nurse, young widow Joan Redfern, and shares his journal with her. Martha is concerned, as the Doctor did not instruct her on what to do should he fall in love. She also struggles with her lowly position at the school, but her resentment at the arrogant public schoolboys is tempered by the knowledge that many of them will die in the upcoming World War I. Timothy Latimer, a young student at the school who has extrasensory perception, discovers the fob watch and pockets it for himself.
The Family of Blood have tracked the Doctor to Earth, and cloak their ship in a nearby wood with an invisibility shield to keep it hidden. The Family seek out humans to possess, and take the bodies of several people including one of the schoolboys, Jeremy Baines. When Timothy briefly opens the fob watch and experiences portions of the Doctor's memories, the Family detects its presence at the school. They try to get information from Martha about the Doctor when she realises that the Family has found them and attempts to retrieve the watch but cannot find it. She talks to John and tries to awaken his Time Lord self, but instead causes him to become angry with her and fire her. John asks Nurse Redfern to accompany him to the village dance that night, and she accepts. At the dance, Martha again tries to persuade John to become the Doctor by showing him elements of his past such as his sonic screwdriver. Now aware that John Smith is the Doctor, the Family interrupt the dance and confront him. In a cliffhanger ending, they take Martha and Joan as hostages and give John a choice to either become a Time Lord again or watch his companions die.
Human Nature