Margaret Cain

Margaret "Maggie" Cain (28 December 2028-21 November 2059) was a member of the Bowie Base One crew.

Early life and career
Born in Grenoside, Sheffield on 28 December 2028, she graduated from the University of Sheffield with a first-class honours degree in chemistry. Her first job was as an engineer for a division of the GEC in London, where she also began studying part time for a PhD at Birbeck College. She was a British cosmonaut on the Russian Federal Space Agency mission Project Midas, beating over twenty-five thousand other candidates. In 2051, Margret became the second British woman to walk on the moon. She met the first, Adelaide Brooke, and the two developed mutual respect. Consequently, Brooke asked Cain to join the Bowie Base One mission.

Colony on Mars
She arrived at the base in 2058 and worked there, studying the planet Mars. She was attacked by Andy Stone after he was infected with the Flood virus, falling unconscious before being found by Tarak Ital, Adelaide and the Tenth Doctor in the biodome corridor. After being placed in sickbay, she awoke and attempted to get Yuri Kerenski to open the door for her to come out.

Infected by the Flood
During a conversation with Yuri, Maggie's virus became active. The Flood occupying her body revealed its desire to reach Earth, a planet rich in water. A shocking Yuri informed Adelaide as to what had happened. In the medical dome, the Doctor and Adelaide met the infected Maggie, who just stared at them all, but took an interest in the Doctor when he speaks Ancient North Martian to her, appearing to understand it. After Yuri evacuated the Medical Dome, Maggie brke out of confinement and alerted Andy and Tarak in the biodome corridor by emitting a scream.

With the other infected members, she tried to infect the remaining crew and escape to Earth, infecting Ed Gold, who blew up the ship before his transformation, killing himself and stranding the Flood on Mars. After Steffi and Roman were infected by the Flood, Maggie and the other infected personnel went to the glacier, and screamed in order to crack the ice. Maggie and the other infected personnel were killed when Adelaide blew up the entire base. (TV: The Waters of Mars)

Behind the scenes

 * The Doctor's flashback to Maggie's obituary notes that she was from Grenoside, Sheffield, and was a chemistry graduate from the University of Sheffield, two things she shared with, the first Briton in space.
 * Like the other female member of the Flood, Steffi Ehrlich, she kept her eye colour. It seems the males had milky, blue eyes while females kept their colour. The Doctor noted this during the episode and suggested that it meant she was closer to human than the others.