Doctor Who: The Creeping Death (3.3)

London, 1952, and a deadly smog envelops the capital. But something even more dangerous - and alien - is hiding within the mists.

When the Doctor and Donna get lost in the fog, they find a motley group of Londoners trying to make their way home.

Very soon, the stakes are raised, as death creeps along fume-choked streets, and not everyone will make it out alive...