Base under siege! In space! With spaghetti mouthed aliens!

Fans gravitate to stories like these. Weighty, grown up adventures which make us feel very serious and legitimate in obsessing over our favourite children's family TV show. After the comic campery of The Idiot's Lantern we are thrown into the depths of hell where our hero meets the literal Devil incarnate.

Not just our hero either - a whole cast of convincing, engaging characters who (with the exception of Danny) give a sense of realism to their environment. The feeling the convey is similar to that of Terry Nation's Survivors - these are a surviving cast of crew on a doomed mission, being picked off one by one by a malevolent, unknown force. The fact that Danny is so unconvincing I think speaks volumes about the quality of the acting going on around him.

The Doctor and Rose's chemistry finally hits home here. They feel like a perfect couple, destined to be together. Their natural believability took a bit of a hit for me when Eccleston changed to Tennent, but now its as glorious as ever.

The Ood are an excellent invention - brilliant writing paired with a perfect visual. The servant race who are not naturally menacing but susceptible to being taken over. This is without a doubt the most successful original creature introduced to Doctor Who in the 21st Century.