16 - New Beer, Same as the Old Beer (S2, Ep1)

We watch 10th Doctor's first full episode titled "New Earth" (Series 2, Episode 1) where the Doctor and Rose visit New Earth (oh, clever) 23 years after Old Earth blowed up real good. Whilst there, they meet up with some old acquaintances and save New Earth from evil Cat Nuns. Nun Cats?