The TARDIS lands in Pompeii the day before the eruption of Mount Vesuvius in AD 79. The Doctor (David Tennant) and Donna Noble (Catherine Tate) explore the city. Discovering that a local merchant has sold the TARDIS to sculptor Lobus Caecilius (Peter Capaldi), they go to Caecilius’s house to get it back. A soothsayer (Karen Gillan) follows them and reports to the Sibyline sisterhood that the prophecy of the Man in the Blue Box is coming true, and he will bring fire and death.
At the house, the Doctor and Donna meet the local Augur, Lucius Petrus Dextrus (Phil Davis) who is there to collect a sculpture. The Doctor notices a sculpture that resembles a circuit board and asks Caecilius’s son Quintus (Francois Pandolfo) to help him break into Dextrus’s’ house. He determines that the circuits are for an energy converter.
They are caught by Lucius Petrus, who summons a creature made of stone to attack them, but Quintus douses it in water and kills it. In the ruckus, the Sisterhood kidnap Donna, and the Doctor sets out to rescue her. He discovers that the Sisterhood is being controlled by Pyroviles, whose home planet of Pyrovilia was lost. With Donna, he escapes into a tunnel that leads into the heart of Mount Vesuvius.
The volcano is being used by the Pyroviles to—you guessed it—conquer the Earth. The volcano will not erupt if the energy converter is running, but the Doctor declares that the eruption is a fixed point in Time and must happen. The Doctor and Donna climb into an escape pod and overload the converter, triggering the eruption, killing the Pyroviles and ejecting the pod to safety.
As they run for the TARDIS, Donna begs the Doctor to save Caecilius and his family. The Doctor does this and leaves them on a hill to watch the destruction. Six months later Caecilius’s son gives thanks to his household gods--a bas-relief carving on the wall of the Doctor, Donna, and the TARDIS.
Some of the sets were from the TV series Rome, but much of the episode was filmed at the Cinecitta Studios in Rome, the first time the series revival went abroad for filming. Ironically, there was a fire before filming which caused delays and killed four people. Critical reviews were mixed. The moral conflict between the Doctor and Donna was praised, but the writing and some of the acting were criticized. Peter Capaldi (Caecilius) would later become the Twelfth Doctor and Karen Gillan (Soothsayer) would be a companion of the Eleventh Doctor. The Doctor says he is Spartacus and Donna says, “So am I.” The Caecilius family were real people in Pompeii, used in a popular British Latin-language textbook. The line, “You must excuse my friend, she’s from Barcelona,” is a twist on an oft-repeated line in Fawlty Towers.
Filming abroad, as always, caused problems. The equipment truck was delayed at the Swiss border, the special effects team were delayed in Calais, and they ended up with only 48 hours to film the whole story. The First Doctor, William Hartnell, visited Rome in 1963, in an episode that ended with the Great Fire of Rome. The Tenth Doctor insists he did not start “that fire” but he did accidentally give Nero the idea. When the Doctor is about to be arrested, he says “Morituri te Salutant,” which means “We who are about to die salute you,” the phrase spoken by gladiators before combat. The eruption in Pompeii happened the day after the Vulcanalia, the day of worship of Vulcan. Until then, there was no word for Volcano in Latin. Catherine Tate’s portrayal of Donna Noble’s vain attempts to save lives are the moral highlight of the episode, and she is instrumental in changing the Doctor’s outlook on human life.