In one of the best two-parters of the Russell T Davies era, the Doctor faces off against the Devil himself. While this seems like it could have been a shark-jumping moment, the episode pulls it off quite well. Perhaps its best aspect is the serious examination of the relationship between the Tenth Doctor and Rose, as they come to terms with how they feel about each other. The pre-credit sequence starts with an unbearably smarmy joke between them, and then quickly intensifies as they find mysterious writing on the wall with a warning, followed by an attack from the unfamiliar Ood who declare that they must feed... them, if they are hungry. The scene immediately after the credits shows the Ood to actually be harmless (at first), but it's still a cracking start to what is one of Doctor Who's most surprisingly scary episodes to date.
