Roots: Historical accounts from Pliny the Younger. In addition to this many of the characters are based on real people recorded in Pompeian ruins (Murranus comes from an inscription in the Amphitheatre, a statue of Eumachia survives, plus reference is made in a painting to the patron Popidius Celsinus, restorer of the temple of Isis).
Intertextuality: Captain Muriel Frost of UNIT originates in Doctor Who Magazine's comic strip.
Fluffs: Slim pickings this time, but you'd think with Aglae being surrounded by Romans all day and all, she'd be able to muster a decent pronunciation of 'necropolis'.
Fashion Victims: 'I'm drawing attention? Whereas question-mark pullovers are the height of discretion I suppose?' More like fashion abettors - Mel adopts Roman garb to fit in with ease, and in doing so virtually inspires the events of the next three episodes.
Dialogue Disasters: Breathless in Pompeii - 'And who might you be girl, that you presume to speak so to a priestess of the Panthetonian Triad?'
Dialogue Triumphs: The Doctor in a sullen mood: 'Time's slipping away from me - only just arriving. But we've already stayed a lifetime. Too many lifetimes, withering like roses...'
Mel's confessed dietary preferences are misunderstood: 'Is this Vegetaria far from here?'
'It doesn't seem fair' '-Time never is'
Continuity: The TARDIS has been malfunctioning and 'won't tell' the Doctor where they have arrived. Mel has never seen a real volcano before and knows who UNIT are. She gives her full name as Melanie Bush, and says she's a vegetarian. She mentions school twice: she made a replica of Mount Vesuvius out of papier mâchè at primary school, and she learned Latin (in fact, her familiarity with Roman customs seems quite sound).
In 1980 the ash-bound TARDIS is uncovered from among the ruins of Pompeii by an earthquake recovered by Professor Scarlini. Captain Muriel Frost of British UNIT identifies the Ship. Some time [possibly a year or so] later, UNIT contacts the [fifth?] Doctor in London and shows him a file covering the appearance. The newly arrived Doctor's TARDIS is at the time situated on Hyde Park corner.
The Doctor hypnotises Celsinus, seemingly by only speaking to him quietly.
After the eruption buries the TARDIS the Doctor and Mel stay 'cooped up' inside for three days while the surrounding ash cools and hardens, leaving a solid chamber from which the Ship can dematerialise. It later materialises in time to be uncovered by a 1980 earthquake and found by Professor Scarloni's archaeological team, being reported later to Captain Muriel Frost of UNIT UK. Having been returned to UNIT headquarters in Italy they then leave discreetly.
Untelevised Adventures: Some time in the 1980s whilst in his fifth incarnation the Doctor reads UNIT documents that tell of the TARDIS's discovery in Pompeii.
The seventh Doctor navigates Pompeii with ease, suggesting he has at least some familiarity with its layout of the time.
Location: Pompeii, 79AD, a few days over the Festival of the Vulcanalia on the tenth before the Calends of September (i.e. August 23rd).
The Bottom Line: 'I wish I could help you - I wish I had time to help everybody'
A real race against time and predestination, 'Fires' offers vindication to the dedicated defenders of Bonnie Langford's Mel. Meanwhile the Doctor broods, fearing the end of his travels, but possibly laying out the terms of Mel's imminent departure, slipping her lines such as 'It's your decision, Mel - it has to be your choice'. A curious mix then of traditional historical (the educational bent of the opening scenes harks right back to the Hartnell era) and fan theorising (courtesy of Lyons' own Virgin New Adventure Head Games).