A planned trip to Ancient Rome sees the time travellers land instead in Pompeii, AD 79. The Doctor knows that they have arrived on the eve of the eruption of Mount Vesuvius, but before he and Donna can retreat to the TARDIS, they discover that there is an alien presence at work in the city. Seers are exhibiting extraordinary flashes of precognition and telepathy, even as they slowly turn to stone. Soon it appears that the destruction of Pompeii may not be a natural occurrence at all, but the work of the volcanic Pyroviles.

When executive producer Russell T Davies began the work of reviving Doctor Who in 2003, one of his earliest ideas was an adventure based around the cataclysmic eruption of Mount Vesuvius, which engulfed the Roman city of Pompeii in AD 79. Davies had long been engrossed by the event, and his interest was piqued again when he viewed the docudrama Pompeii: The Last Day in October 2003. Davies considered writing a script about Pompeii for the eleventh episode of Doctor Who's 2005 season, but it quickly became clear that this would have to be a budget-conscious adventure; Davies eventually wrote Boom Town instead.

Davies did not forget about the Pompeii idea, however, and in readying his fourth Doctor Who season in early 2007, he again began considering its plausibility. At this point, it was planned that the third episode of the year would be a script by Mark Gatiss (who had written The Unquiet Dead and The Idiot's Lantern) involving Nazis during World War II. Gatiss had been working on the story for more than a year, but Davies was concerned that it was too soon to revisit that period of history after 2005's The Empty Child / The Doctor Dances. He began contemplating replacing Gatiss' script with a Pompeii adventure.

To this end, Davies asked that the logistics of recreating ancient Rome on a Doctor Who budget be investigated. It became clear that the best way this could be accomplished was to make use of the extensive sets built for the BBC/HBO coproduction Rome, which were located at Italy's historic Cinecittà studios in Rome itself. One of the most renowned studios in Europe, over the years Cinecittà had housed such famed productions as Ben-Hur (1959), Quo Vadis (1951), and many films by Federico Fellini, such as La dolce vita (1960). It transpired that Cinecittà was very eager to market its facilities as an attractive destination for British productions, and so was willing to do whatever it could to work within Doctor Who's financial limitations. This was all the encouragement that Davies needed, and at the end of April, he decided to replace Gatiss' story with a new episode set in Pompeii.

However, with only four months remaining before the Pompeii episode would have to be recorded at Cinecittà, Davies knew that he would have to find a writer who could work on the scripts very quickly. He decided to turn to James Moran, who had impressed Davies with his work on Sleeper for Torchwood's second season. Moran had broken into television after winning a script competition run by the Sci-Fi Channel in the UK. He had then gone on to write the horror-comedy Severance before being invited to contribute to Torchwood. Davies felt that Moran was a talented writer who could handle the work of shaping the early drafts of the Pompeii story, but who also wouldn't mind Davies taking over and polishing the script into its finished form. Moran was formally offered the job on May 9th.

During the summer, Moran's adventure became known as The Fires Of Pompeii. Davies was adamant that the script deal with the moral quandary of the Doctor leaving an entire city full of people behind to die in accordance with recorded history, and this prompted the inclusion of a regular Roman family as main characters. The family was inspired by the first book of the Cambridge Latin Course (originally published in 1970), which focussed on a banker named Lucius Caecilius Iucundus, his wife Metella, and his son Quintus. The course also featured an unpleasant soothsayer named Lucius Marcius Memor. For the latter's analogue in The Fires Of Pompeii, Davies amended the name to Lucius Petrus Dextrus -- “Petrus Dextrus” alluding to the fact that Lucius' right arm has turned to stone. Moran originally named his aliens Pyrovillaxitrians (from the Greek “pyr”, meaning “fire”). He gradually shortened this to Pyrovillaxians and then Pyrovellians before Davies amended this to Pyroviles.

In early August, Davies decided to move The Fires Of Pompeii up to become the second episode of the 2008 season, swapping places with Planet Of The Ood, in part to showcase the planned Cinecittà shoot. Around now, however, Davies was mired in the depths of a scripting crisis: he was rewriting The Fires Of Pompeii and was also supposed to be deep into the process of developing the season premiere, Partners In Crime, but was making little progress with either one. The two episodes were intended to form the year's third production block, to be directed by Colin Teague. Since helming The Sound Of Drums / Last Of The Time Lords, the finale of Doctor Who's 2007 season, Teague had also worked on the Torchwood episodes Sleeper and Meat.

For a time, Davies contemplated dropping The Fires Of Pompeii and restoring Gatiss' Nazi adventure in its place. Finally, however, it was decided that The Fires Of Pompeii and Partners In Crime should each form their own recording block, with the latter handed to James Strong to direct as Block Four. This meant that Davies could concentrate on completing The Fires Of Pompeii, since the delivery date for Partners In Crime would be later than originally planned.

Yet another calamity nearly struck The Fires Of Pompeii in August. Producer Phil Collinson and production manager Tracie Simpson had been making periodic visits to Cinecittà throughout the summer. During one of these visits, on August 9th, they were alerted to the fact that an area of the historic studio was on fire. The conflagration was the result of an electrical short, and caused the deaths of four people and considerable destruction before it was extinguished. Despite the tragedy, however, the sets required for The Fires Of Pompeii had not been damaged, and so work on Doctor Who could proceed according to plan.

The arrival of David Tennant and Catherine Tate in Italy on September 12th marked a milestone for the revival of Doctor Who. Although plate shots had been recorded in New York City for 2007's Daleks In Manhattan / Evolution Of The Daleks (and the 1996 Doctor Who TV movie had been filmed in Vancouver), the making of The Fires Of Pompeii was the first time that an ongoing Doctor Who series had taken its principal cast abroad since The Two Doctors was recorded in Seville in 1985. Work at Cinecittà took place on the 13th and 14th, covering all of the material in the streets of Pompeii. The next day, plate shots were captured at Mount Vesuvius itself.

The production then shifted back to Cardiff, where scenes in the Sibylline temple were taped at the Temple of Peace on September 18th and 19th. Next to be recorded were the sequences in Caecilius' home in Pompeii, which was constructed at Upper Boat Studios. This work spanned the 20th to the 27th; the only exceptions were the 23rd, which was a day off, and the 26th, which concentrated on material in the Pyrovile control sphere and in Caecilius' new dwelling in the city of Rome.

On September 28th, Clearwell Caves near Coleford in Gloucestershire provided the rock tunnel leading to the Pyroviles' lair, as well as the point of view shots of the Pyrovile in the hypocaust. Recording then resumed on October 1st at Morlais Quarry in Merthyr Tydfil, for all of the scenes on the slopes of Mount Vesuvius. This left only the material under the mountain, filming for which was completed at Taffs Well Quarry in Taffs Well on the 2nd. Later that month, on the 20th, an insert shot of the Doctor firing his water pistol was taped at Upper Boat.

• Outpost Gallifrey: New Doctor Who Series News Page, edited by Shaun Lyon.
• Doctor Who Magazine Special Edition #20, 19th November 2008, “Episode 2: The Fires Of Pompeii” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Writer's Tale by Russell T Davies and Benjamin Cook (2008), BBC Books, ISBN 978 1 846 07571 1.