The following are previews of this episode which aired November 15th, 2009.
From Wikipedia: “The story is set on Mars[10] and the Doctor will be joined by a new companion named Adelaide, played by Lindsay Duncan, who is head of the Mars base.[3] Producer Nikki Wilson described the character as “the Doctor’s cleverest and most strong-minded companion yet.”[6] The most recent trailer shows a massive Terrarium of life on the planet’s surface, and a mysterious alien which infects its victims using a water compound it creates.
In the BBC trailer, the Doctor says that the events ongoing on Mars are a fixed point in time and must not be changed.
This promises to be a darker episode.
