The Doctor is in present-day London and hops on a number 200 bus that suddenly travels through a wormhole. He and the other passengers find themselves in the middle of the desert which he later determines to be on a planet in a galaxy clear across the universe. Aboard the bus one of the passengers is Lady Christina de Souza, a rather accomplished thief who was on the run after having successfully stolen a very valuable piece from a museum. She's quite enthusiastic and proves to be quite helpful as The Doctor tries to unravel what has happened to them and most importantly, devise a means of returning, given that the bus is firmly stuck in the sand and heavily damaged. Back in London, Captain Erisa Magambo has taken charge of the situation and faces the prospect of having to permanently close the wormhole before the travelers can return.
