Death on the Mile (audio story)

 was the fourth and final story in the audio anthology Lady Christina: Series One, produced by Big Finish Productions. It was written by Donald McLeary and featured Michelle Ryan as Lady Christina de Souza, Warren Brown as Sam Bishop and Tracy Wiles as Jacqui McGee.

Publisher's summary
Lady Christina has been offered a job: the heist of a lifetime. She simply has to break into Edinburgh Castle.

At the same time, UNIT are investigating alien activity at the Military Tattoo. And where there's treasure and treachery, there are also Slitheen...

Plot
When Robin is oddly nice to her, Elaine calls her old friend Jacqui McGee. Elaine meets with her at their old university café and asks her to help find out why Robin is uncharacteristically happy all the time. Jacqui finds Robin and tries to get him to play his bagpipes, but he declines. Later, Elaine finds that Robin has disappeared with all of his equipment and asks Jacqui to track him down.

Christina steals a necklace at the Albert Hall and meets Sir Edward Scott Cameron, who offers her a new mission: stealing George II's war chest from Edinburgh Castle. She travels there in the 200 and uses truth venom to learn how to get in, but she is stopped by Biggs whilst attempting to drive in in a bin lorry. She knocks him out and tells Janice Matheson that she is working for a cooking magazine, giving her the opportunity to find the secret anteroom and use a matter displacement manipulator to dig up the chest.

Upon acquiring the chest, Sir Edward, Handley, Robin and Janice reveal that they are Raxacoricofallapatorians of the Clan Gleff-Cotch Slitheen and that they have captured Sam, who was sent to Edinburgh after UNIT detected exotic energies there. They remove their skin suits and prepare to kill Christina and Sam to take the treasure to pay their off-world debts, but Jacqui walks in and kills two of them with pickled onions and gherkins. The remaining Gleff-Cotches escape using the matter displacement manipulator and detonate a device to liquify the rock beneath the castle, making it an active volcano.

Christina, Sam and Jacqui escape in the 200 and avoid the lava bombs and the military's cannons and Christina uses a beam to divert the lava with a trench. The amount of energy used causes the 200 to crash into the sea, but Christina puts it into amphibious mode and, after Jacqui receives a text from Elaine, flies to Elaine and Robin's fifth-floor flat. They break through the window and Christina kills the Slitheen Robin with vinegar, after which the Slitheen Edward escapes with the treasure using the matter displacement manipulator. He returns to the Slitheen spacecraft, a converted monument to Wallace, and takes off.

The 200 gives chase and smashes into the Slitheen ship, causing both vehicles to fall and crash into King Arthur's Seat, the war chest opening to reveal only paper money inside. The Slitheen Edward is mortally wounded and turns the hill into an active volcano as well. With the matter displacement manipulator destroyed by Sam to prevent the Slitheen Edward from escaping, Christina uses the 200's beam to move Edinburgh Castle and put it on the hill to plug the volcano. She gets Sam, Jacqui and Elaine off of the bus, saying that it is about to explode, and flies into the sea. Sam, Jacqui and Elaine hear an underwater explosion, but UNIT reports indicate that the explosion was caused by fireworks and that the 200 has been spotted near Skye Bridge.

Christina decides to head to Reykjavik where a collection of sapphires is on display, one of which potentially comes from Metebelis.

Cast

 * Lady Christina de Souza - Michelle Ryan
 * Sam Bishop - Warren Brown
 * Jacqui McGee - Tracy Wiles
 * Elaine / Janice / Slitheen Janice - Melissa Collier
 * Robin / Slitheen Robin - Richard Hansell
 * Sir Edward Scott Cameron / Slitheen Edward / Biggs - Ewan Bailey
 * Handley / Slitheen Handley - Christopher Ryan
 * Policeman - Gareth Corke

Worldbuilding

 * Elaine and Robin eat steak pie.
 * Elaine had to give up her job to care for her mother.
 * Robin is in the Loch Earn Pipe Band.
 * Sir Edward offers Christina champagne.
 * The Seven Years' War was fought between England and France.
 * Christina uses truth venom.
 * Christina did ballet for several years.
 * Christina has a matter displacement manipulator, or MDT.
 * Christina mentions fidget spinners.
 * Christina is distantly related to George II. She says that she has his eyes.
 * The disguised Slitheen suffer from gas exchange.
 * The Raxacoricofallapatorians belong to the Clan Gleff-Cotch Slitheen of the northern Gleff-Cotches.
 * Vinegar is used to kill Slitheen.
 * The "Slitheen Edward" is the grandmother of the "Slitheen Robin".
 * Christina says that she is not Bill Gates.
 * The 200 has a SatNav.
 * Sam says that Osgood has her work cut out for her.

Continuity

 * Sam mentions the UNIT massacre at Downing Street. (TV: Aliens of London, World War Three)
 * Christina claims that the 200 was a "gift". (TV: Planet of the Dead)
 * Christina plans to check a collection of sapphires, one of which is reportedly from somewhere called Metebelis. (TV: Planet of the Spiders, AUDIO: Worldwide Web)
 * After her last adventure with Sam Bishop, Christina has installed a remote control and an "amphibious mode" to the 200, enabling the bus to survive and navigate underwater. (AUDIO: Portrait of a Lady)
 * The Slitheen are suffering from the gas exchange. (TV: Aliens of London et al)
 * UNIT is fully aware that vinegar is deadly to the Raxacoricofallapatorians. (TV: World War Three, Revenge of the Slitheen, AUDIO: The Taste of Death)
 * Christina refers to 200 as "old girl", just like how the Doctor refers to his TARDIS. (TV: The Doctor's Wife et al)