The Fires of Vulcan (audio story)

 was the twelfth monthly Doctor Who audio story produced by Big Finish Productions. This was the third full story to feature Sylvester McCoy as the Seventh Doctor but the first audio story to feature Bonnie Langford as Melanie Bush, a role which she last played in the non-canonical Children in Need sketch Dimensions in Time in 1993. This was also writer Steve Lyons' first contribution to an audio story; he has also contributed to a number of novels and short stories.

Publisher's summary
Two thousand years ago, a cataclysmic volcanic eruption wiped the Roman city of Pompeii from the face of the Earth. It also buried the Doctor's TARDIS...

Arriving in Pompeii one day before the disaster, the Seventh Doctor and Mel find themselves separated from their ship and entangled in local politics. With time running out, they fight to escape from the shadow of Mount Vesuvius. But how can they succeed when history itself is working against them?

Plot
An archaeological dig in Italy has turned up something strange—so strange, in fact, that UNIT, under the command of Captain Muriel Frost, has been called in. But how did a certain—and very familiar—blue police box wind up buried in the ruins of Pompeii?

The TARDIS has landed, but with an odd fault: it won’t tell the Doctor where or when it has materialized. Upon exiting, the Doctor and Mel meet a slave, Tibernus, who takes them for emissaries of the goddess Isis. He tells them it is the twenty-third of August; and the Doctor makes a sudden realization: it is the year 79 AD, and they have landed in Pompeii—and it’s volcano day!

Or, almost. Mount Vesuvius will erupt tomorrow, in fact, at mid-day. The Doctor, preoccupied, lets Mel decide whether to leave or stay; she opts to take a look around. In the city, her odd clothes attract the attention of the decurione Popidius Celsinus, of the city’s municipal court. He is intrigued by the rumor that they are messengers of Isis, as that goddess is his patron. Meanwhile, Tibernus reports to his owner, Eumachia, who is also displeased with the news.

The travelers quickly make new—and not altogether good—acquaintances. The Doctor meets, and subsequently (by exposing his cheating at dice) offends, a disgraced gladiator named Murranus, who thereafter swears revenge on him. Mel meets another slave, a brothel slave named Aglae. Both are interrupted by an earthquake. Mel is disturbed to find that the locals dismiss the quakes as the displeasure of the gods; they refuse to accept any actual danger. However, there’s a problem: the TARDIS is gone, buried beneath a building that collapsed in the quake. Unable to dig it out on their own, the Doctor and Mel are now trapped. The Doctor is strangely unsurprised; finally he tells Mel that he expected this, as he knows that the TARDIS, in the year 1980, will be dug from the ruins of Pompeii. He has encountered this before, in his fifth life, courtesy of UNIT; and now the time has come.

Mel refuses to accept defeat, and promises to solve their situation. She goes to seek help, while the Doctor returns to the inn—owned by a woman named Valeria—where he humiliated Murranus, who is now thankfully not present. Elsewhere, Eumachia meets with Celsinus, and tries to get him to help her expose the Doctor and Mel as impostors. She also buys some of Aglae’s time at the brothel, and questions her, then beats her. Mel interrupts and stops her, but Eumachia is not deterred. Later, Celsinus invites Mel to dinner; she accepts, knowing that he has the means to get help in digging out the TARDIS. The Doctor joins her there, as does Eumachia. The dinner goes badly, and ends in an argument; however, the Doctor has come to his senses now, and vows to do what he can to save himself and Mel, though he knows he is fighting time and paradox itself to do so. In the meantime, he tells Mel to leave the city so that she will survive if he runs out of time. However, Eumachia brings a squad of guards and has Mel arrested, on (admittedly false) charges of theft.

During the night, the Doctor realizes he has overlooked something both obvious and important. He drafts Aglae to help him rescue Mel. Meanwhile, Celsinus visits Mel in the local gaol. She admits that she lied about being a messenger of Isis, but denies the theft. After some debate, he decides that she is probably innocent, and that he was manipulated by Eumachia; he determines to have her freed—and it should only take a few days…Mel, dismayed, sends him away. She barely has hours, let alone days. The Doctor meets him on the way out, however, and hypnotizes him—along with the guard on duty—and frees Mel. Aglae will take her out of the city, and the Doctor will search for the TARDIS; he realizes that the building that collapsed was excavated much earlier than 1980, meaning it is not the location where the TARDIS was found. The TARDIS, therefore, has been moved.

Mel and Aglae try to leave the city, but are caught by a gate guard. Aglae knocks out the guard, and they hide in the nearby necropolis. They are caught again by the same guard when they try to leave in the morning, and locked up again.

The Doctor returns to the inn, but Murranus—who is fortuitously drunk—is there. Murranus threatens Valeria into helping him capture the Doctor; she does so, against her will, by drugging the Doctor’s drink.

Celsinus meets with Mel again, and she tells him the whole truth. He doesn’t want to believe it; but he tells her that Eumachia has described the TARDIS, and when she confirms its detailed description, he believes her. He releases Mel and Aglae, just as another tremor strikes. Vesuvius is about to erupt.

The Doctor awakens in the local amphitheatre, where Murranus waits. He is forced to fight. At first he refuses, but Valeria comes to his defense, and he is forced to fight back to save her. He is about to be killed…when the mountain erupts.

In the ash and darkness, the Doctor and Valeria escape; Valeria believes he must be a messenger from the gods after all, if he has power to make the mountain explode. He brushes that aside, and sends her away, warning her to flee the city.

Mel leaves Aglae with Celsinus, and makes her way to Eumachia’s house. Eumachia admits to taking the TARDIS, but refuses to reveal its location; she insists that the ongoing destruction is because of Mel. Tibernus reveals that the TARDIS is in the necropolis, but he does not know which tomb; he only has an approximate location. He refuses to flee, choosing to stay with his mistress even in the face of death. He and the other slaves will die, as will Murranus and the other gladiators, who have retreated to their barracks.

The Doctor meets up with Celsinus and Aglae, and passes Valeria to them, warning them all to flee. They do so, but lose Valeria in the crowd; history will record that she died in Pompeii. They escape the city, but their fate is unknown. Meanwhile, the Doctor finds Mel, and they make their way to the necropolis…and as the city chokes on ash and smoke, they locate the TARDIS, just in time.

The TARDIS materializes in 1980, just before the earthquake that unearths it. Mel comments on the fate of their friends, and the Doctor reflects that they may have survived; he does not know, but chooses to believe they survived until he sees proof to the contrary. She asks why they spent three days waiting in the TARDIS before leaving. The Doctor says that it is so that the ash and lava would harden around the TARDIS, forming a TARDIS-shaped cavity, into which he then materialized it in 1980. Thus the timeline is preserved, and no paradox results. They exit the TARDIS and hide just in time to see Captain Frost approaching the scene of the discovery; in a few days, they will go to UNIT and reclaim the TARDIS, and be on their way.

Cast

 * The Doctor - Sylvester McCoy
 * Melanie Bush - Bonnie Langford
 * Professor Scalini - Anthony Keetch
 * Captain Muriel Frost - Karen Henson
 * Tibernus - Robert Curbishley
 * Popidius Celsinus - Andy Coleman
 * Valeria Hedone - Nicky Goldie
 * Murranus - Steven Wickham
 * Eumachia - Lisa Hollander
 * Aglae - Gemma Bissix
 * Priest - Toby Longworth
 * Roman Legionary - Robert Curbishley

The Doctor

 * During his fifth incarnation, the Doctor was contacted by UNIT, who told him that they had found his TARDIS encased in rock at Pompeii during an archaeological excavation in 1980.

Individuals

 * Mel states that she is a vegetarian. Valeria Hedone responds that she has never heard of Vegetaria.
 * Mel made a replica of Mount Vesuvius out of papier mâchè while at primary school.

The Master

 * The Doctor uses his voice to compel a guard and later Popidius into handing over a key and going to sleep, a skill previously demonstrated by the Master.

Earth history

 * According to the Roman calendar, 23 August is the tenth day before the Kalends of September.

Continuity

 * An older version of the Seventh Doctor would later return to Pompeii in August 79 in the company of Ace (PROSE: The Algebra of Ice), as would the Tenth Doctor and Donna Noble (TV: The Fires of Pompeii) and his future travelling companion Captain Jack Harkness, on multiple occasions (TV: The Doctor Dances).
 * The Seventh Doctor is unaware that the eruption of Mount Vesuvius was triggered by his tenth incarnation in order to kill the Pyrovile. (TV: The Fires of Pompeii)