Born in Grenoside, Sheffield on 28 December 2028, she graduated from the University of Sheffield with a first-class honours degree in chemistry and then went into engineering. She was a British cosmonaut on the Russian Federal Space Agency mission Project Midas, beating over twenty-five thousand other candidates. In 2051, she 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.
She arrived at the base in 2058 and worked there, studying the planet Mars. She was infected with a virus, known as the Flood. It changed her body form. With the other infected members, she tried to infect the remaining crew and escape to Earth, but failed, due to the actions of the Tenth Doctor. While infected she appeared to act as the leader of the Flood infectees. She had a voice powerful enough to crack the ice holding the main body of the Flood. She was blown up when Adelaide, her captain, took "Action Five" and destroyed the 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 Helen Sharman, 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.