2.0 - The Christmas Invasion

From IMDB:
The newly regenerated Doctor travels to present day London and Rose is happy to be home. Her mother is happy to see her, her protestation to the contrary. The Doctor isn't well however suffering from what he describes as a surplus of energy. While he is in a coma-like state, the people of the Earth are threatened by the Sycorax who threaten to destroy one-third of the planet's population if they don't surrender. The Prime Minister, in the apparent absence of the Doctor, asks for assistance from Torchwood but it's slow in coming and the end is fast approaching. Rose's mum Jackie has the cure for the Doctor, however.

15 out of 37 (40.5%) raters say this story requires a previous story.