"Boom Town" is the eleventh episode of the first series of the British science fiction television programme Doctor Who. The episode was first broadcast on BBC One on 4 June 2005. It was written by executive producer Russell T Davies and directed by Joe Ahearne. The episode is set in Cardiff in the early 21st century, six months after the 2005 episode "World War Three". In the episode, the criminal alien Slitheen named "Margaret Blaine" (Annette Badland) attempts to gain her freedom after being captured and detained by the alien time traveller the Ninth Doctor (Christopher Eccleston). "Boom Town" was a replacement episode for a story that was to be written by Paul Abbott, but he had to abandon the script because he had other commitments. Davies decided to write a different story centred on bringing Badland's character back from the fourth and fifth episodes of the series, "Aliens of London" and "World War Three", as he had enjoyed her performances. Primarily, Davies wanted to explore the consequences of the Doctor's actions and question whether he had the right to sentence an enemy to death. The episode was also intended to showcase Cardiff, where the revived Doctor Who series is made, and where the episode was filmed in February 2005. "Boom Town" was watched by 7.68 million viewers in the United Kingdom and received mixed reviews from critics. Plot The Ninth Doctor lands the TARDIS in Cardiff, using the energy of the Cardiff Rift to recharge the engines of the time machine. Mickey joins the Doctor, Rose, and Jack for lunch. The Doctor spots a newspaper article showing Margaret Blaine, a Slitheen, has become Cardiff's new mayor. The four track down and capture Blaine to find out what she is doing there. The Doctor observes Blaine's scale model plans for a new nuclear power plant, but realizes that it is purposely flawed to cause a meltdown that would open the Cardiff Rift and destroy the Earth. He also discovers the model contains an "extrapolator" that Blaine would have used to flee the Earth. The Doctor decides to take Blaine back to her home planet of Raxacoricofallapatorius, but she reveals that she has received a death sentence there and will be executed upon returning. The Doctor agrees to her final request to accompany her to dinner in a restaurant. Blaine makes several half-hearted attempts to kill the Doctor but he easily