An aristocrat whose father had lost too much of money to the Icelandic banks, took up a hobby of stealing priceless works of art. Ostensibly to help support herself and her family, but really she did it just for kicks. After stealing the Cup Athelstan from the International Gallery, she ran into trouble when DI McMillan interrupts her escape plans and almost nabs her. In order to get away, Christina hops on the 200 bus to Brixton. The Doctor is also a passenger on the bus investigating signs of a small wormhole. Of course that means the bus and all its passengers are doomed to enter that wormhole and be transported to a distant world.