4.2 - The Fires of Pompeii

From IMDB:
The Doctor and Donna land in the marketplace in Pompeii in 79 A.D., the day before the big eruption and the destruction of the city. The Doctor's destination was actually Rome but he soon realizes his mistake...but not before a market vendor sells the TARDIS to a local businessman, a seller of marble whose daughter may be able to predict the future. Donna sees an opportunity to warn everyone and evacuate the city but the Doctor flatly refuses. When the Doctor learns that those with the ability to see future are slowly turning to stone, he quickly comes to the conclusion that alien beings are operating inside the volcano - and that he has a far greater decision to make than that put to him by Donna.

7 out of 101 (6.9%) raters say this story requires a previous story.