The Lazarus Experiment

[1] Executive producer Russell T Davies has stated that he directed writer Stephen Greenhorn to base this episode on the typical Marvel Comics plotline: "a good old mad scientist, with an experiment gone wrong, and an outrageous supervillain on the loose.

"[2] In present-day London, a 76-year-old man named Professor Richard Lazarus announces on television that he will demonstrate a device that will change what it means to be human.

The Doctor and Martha discover Lady Thaw's body and deduce that Lazarus must drain life energy to keep his DNA stable.

The Doctor explains that Lazarus' transformation is the result of an evolutionary throwback locked away in dormant genes that the machine accidentally unlocked.

Martha and Tish lure Lazarus to the top of the Cathedral's bell tower, and the Doctor manipulates the church's pipe organ to produce the maximum volume it can, turning it up to eleven.

A scene cut from the episode, but included as an extra with the DVD release, reveals that the Doctor participated in the writing of the United States Declaration of Independence and in fact carries a copy of the first draft folded up in the pocket of his dinner jacket.

An outtake of this scene is featured on the DVD as well, in which the Doctor has completely unfolded the document, only for Tennant to realise that he and Agyeman have run out of track.

The extended trailer featured many short clips from upcoming stories: eyeless animated scarecrows and the titular Family of Blood, the return of Captain Jack Harkness, Sir Derek Jacobi in character, Michelle Collins likewise and, briefly, John Simm as the mysterious Mr. Saxon seen smiling for press cameras before the Houses of Parliament and in the Cabinet Room at No.