The Fires of Pompeii is the second episode of the fourth series of the revival of Doctor Who. It stars David Tennant as The Tenth Doctor and Catherine Tate as companion Donna Noble. It features a small role by Karen Gillam, who would later take on the role of Amy Pond. It was written by James Moran.
The episode takes place in Pompeii the day before the eruption of Mount Vesuvius. The Doctor wanted to show Donna Ancient Rome, but as is often the case, his piloting skills were a bit off, and he lands in Pompeii instead. Before he can leave, his TARDIS is taken by a wealthy marble merchant who (in a call back to Fourth Doctor adventure The City of Death) mistakes it for a piece of modern art. Before the Doctor and Donna can leave, they are swept up into the events of that day. Initially, Donna Noble wants to warn the people of Pompeii about the explosion, but The Doctor explains that the destruction of Pompeii is a fixed point in time, that it can not be altered. But The Doctor (and the viewers) find out that the truth is even more than that: Pompeii is the scene of an alien invasion, and the only way that the Doctor can save earth is to destroy Pompeii. He does so, but at the last moment, on Donna's urging, he manages to save one family from the eruption.
Whereas the Voyage of the Damned was the silly type of silly, Partners in Crime was the good type of silly, this episode brings Doctor Who back to epic science fiction, with frightening aliens and a thorny moral dilemma. The episode also went beyond normal in its shooting, since it was filmed on location, a rarity in Doctor Who. Whereas the previous episode introduced the humorous nature of The Doctor and Donna's relationship, this episode takes a more serious look at how she helps to humanize him. It also introduces a theme of The Doctor as soldier versus The Doctor as helper that would be a continuous theme throughout the fourth series.