Roots: Star Wars, Casablanca ("Everyone comes to Starbarf's"), Monty Python's 'Dead Parrot Sketch" ("merely pining for the fjords"), Socrates (in Plato's Dialogues): "The unexamined life is not worth living". Superman ("Very Fortress of Solitude")

Intertextuality: This story introduces Big Finish's spin-off bounty hunter character Vienna Salvatore, who begins her own series of adventures just as soon as I've researched them more fully.

Dialogue Triumphs: "You'll be as snug as a snortis on Vortis"

"He's done a bunk!" "Leaving us to face the music!" "And they're playing a death march!"

Continuity: Fifty years ("annums") have passed since the events of The Acheron Pulse and the Wrath Wars. This story appears to begin one day prior to the Doctor's arrival (episode order in real chronological order would appear to be, roughly, 3, 1, 2, 4), although the Doctor also travels back to a time before that days as well. Twenty years have passed since the Doctor last intervened.

The Wrath Wars were originally between the Wrath and the Drashani Empire (which eventually fell to the Wrath), but more recently spread out to encompass the Earth Empire as well. The Wrath have their own home world, the Shadow Heart on which sits the Wrath Imperial Fortress and within the Imperial Engine, a city-wide bio-electronic machine which houses the psyches of the Wrath's prisoners, operating as an artificial 'free will' by proxy for the Wrath who lack this (an individual free will is seen by the Wrath as too inconsistent) Wrath warp ships leave an antimatter residue.

Tenebris converted the dead planet Thargros (literally half a world, being hemispherical, the missing half having been atomised) to his secret castle base, an exact replica of the Sorshan Royal Palace. There he used DNA retrieved from the royal carcanet to clone Aleona, to regressive effect (each successive clone has a shorter lifespan) Tenebris has perfected his pyrokinetic abilities to be able to throw fireballs.

The marsh moon of Megros V is neutral territory, but is also inhospitable to all tourism. Its mangrove swamps smell "like an Ogron's armpit "Monkey bats (a "chiropteran species" native to the marsh Moon) revere the local carnivorous plants, with which they enjoy a symbiotic relationship.

Stellar Ammonites (Space Snails) are giant gastropods which are used to trawl the space lanes for salvage. Typical of his species Hercules has a control unit in his stomach and secretes a shining trail of electrons in his path. Space snails have great memories.

Starbarf's is on Grip Street on the planet Temperance VII, the Spotel (see: Links) Allendra is on the adjacent Fifth Street; it is cheap, convenient to the nearby spaceport, and infested with cockroaches. At Starbarf's available drinks include Covee (a blue-green non-alcoholic beverage), bloodnuts (which Mr Gravshaw is fond of), banato fruit juice and stoorbuck milk (see: Links) Minoxytin is resumably also a drink. Mr Gravshaw is a fat, seaweed-like creature with a venom gland and a taste for bloodnuts.

Elliptic XII is a world on the very edge of the galaxy

Dremmer eels (see: Links) shed their skin frequently.

Vienna Salvatore is a bounty hunter, presumably not from Earth (she swears on the "seven moons"). Her hovercopter is armed with laser harpoons.

The Doctor uses the TARDIS' vortex drive to generate an antigravity spiral to slow Hercules' descent. At this point in time the Doctor is the most wanted man in twelve constellations, with a bounty of ten thousand galactic credits (enough to buy half a planet) on his head. Vienna uses a memory sifter to ascertain his identity. The Doctor explains that a Time Lord's respiratory bypass is a skill taught to all Time lords enabling them to survive the vacuum of space. He has never driven a Stellar Ammonite before and can sense a morphic catalyst by their smell.

Untelevised Adventures: The Doctor picked up a survival suit on the planet Galvar, which includes a filtration mask covering the wearer's entire face.

Links: The Web Planet (Vortis), mention is made of Galdrium, dremmer eels and Kawdor (The Acheron Pulse); the Doctor recalls affecting a crash landing on a swamp world "a couple of regenerations back" (The Burning Prince) The term "spotel", presumably a portmanteau word for space-hotel, may have been coined by the people who brought you the Spar (The Daleks' Masterplan)

The Bottom Line: "You wouldn't mind drawing me a diagram when you have a spare moment?"

Despite his protestations Johnny Morris gives the Big Finish universe something eerily close in places to a Star Wars prequel makeover with planetoid space stations, weird cantinas and strapping bounty hunters. Chase Masterton slices her ham thickly, but is easily outdone by grumbling space snail Hercules (give him the spin-off instead!). The return of Tenebris still seems a little perfunctory, but given his obvious unhinged-ness at the close of this story, perhaps having all he could want at the end of The Acheron Pulse and not knowing that what he really craved was probably going to kill him is understandable? In conclusion: tricksy, fun in places (with an impish McCoy bumbling through his plan), and better than the Excelis trilogy - just.