Ep 2. The Fires of Pompeii

The Fires of Pompeii is the third episode of the fourth season of Doctor Who. In this episode, the Doctor (played by David Tennant) and his companion, Donna Noble (played by Catherine Tate), travel back in time to ancient Pompeii just before the city is destroyed by the cataclysmic eruption of Mount Vesuvius.

Upon their arrival in Pompeii, the Doctor and Donna begin to explore the city, but soon discover that something strange is happening. The people of Pompeii are acting oddly, and there seem to be creatures lurking in the shadows. Meanwhile, a wealthy merchant named Caecilius (played by Peter Capaldi, who would later go on to play the Doctor himself) and his family are preparing for a grand feast to celebrate their daughter's birthday.

As the Doctor and Donna investigate, they discover that the strange occurrences are being caused by a group of alien creatures who are using the volcanic energy of Vesuvius to power their technology. These creatures have been manipulating the people of Pompeii and plan to use the eruption of Vesuvius to destroy the city and create a massive energy surge that will power their technology for centuries.

The Doctor and Donna work to stop the aliens and save the people of Pompeii, but they are faced with a difficult decision. In order to stop the aliens, they must interfere with history and change the course of events that lead to the destruction of Pompeii. The Doctor is forced to make a choice between saving the lives of the people of Pompeii or preserving the timeline and allowing history to take its course.

As their adventure comes to a close, the Doctor and Donna must deal with the consequences of their actions. They have saved the lives of many people, but they have also drastically altered the timeline and potentially caused unforeseen consequences in the future.

Overall, The Fires of Pompeii is a thrilling and thought-provoking episode that demonstrates the complex moral and ethical dilemmas that the Doctor faces on a regular basis as he travels through time and space. It is also notable for its impressive set design and visual effects, which bring the ancient city of Pompeii to life in vivid detail.