The Auton Infinity (audio story)

, also marketed as Forty: Volume 2, was an audio story written by Tim Foley and featured Peter Davison as the Fifth Doctor, Janet Fielding as Tegan Jovanka, Mark Strickson as Turlough and Jon Culshaw as Kamelion, Brigadier Lethbridge-Stewart and. It also concluded the Fifth Doctor's "jumping time tracks" narrative.

Publisher's summary
Snowdonia. UNIT is running a training exercise with the Brigadier in attendance. Except it isn’t long before things start to go badly wrong. The fake aliens primed to attack the troops might not be so fake after all, and a temporal disturbance attracts the Doctor, Tegan and Turlough into the fray.

Old enemies are on the scene with a deadly plan - but they might be the least of the Doctor's worries.

Because he's recently been sent backwards and forwards through his own lifetime...and he’s finally going to find out why.

Part one
The Doctor, Tegan and Turlough are buffeted around the TARDIS control room for hours after leaving Frontios and eventually materialise in Snowdonia. They wander into a UNIT training exercise and are taken by Sergeant Wharry to the retired Brigadier Lethbridge-Stewart, who explains that the exercise involves an invasion during a peace conference. The soldiers tasked with roleplaying as aliens deviate from the route, however, and the Doctor's diversiform intensifiser detects temporal energy.

Borrowing Wharry's car, the Doctor, Turlough and Captain Mears go to investigate whilst Tegan remains behind with the Brigadier to keep an eye on things, but a jamming signal is emitted from the opposite direction and Mears decides that it needs to be dealt with first to ensure that UNIT are able to communicate. A plastic alien mask latches onto Mears' face and the Doctor zaps it off with his intensifiser, deducing that the Nestene Consciousness is responsible and going to warn the Brigadier. He notices a circus tent and enters with Turlough and Mears, after which they are greeted by gas and a hologram of.

Part two
The gas is a harmless gas from Tersurus and the Doctor uses the Master's console to stop the broadcast of the signal, which actually originates from a distant source. He informs the Brigadier and Veronica Holmes from the Ministry of Defence of the threat of the Nestenes and the Master and learns that Tegan and Wharry have left, confronting the Auton Prodigal and the soldiers being controlled by the masks. After taking the two humans to an abandoned manor, Prodigal shoots Turlough and captures the TARDIS, which she intends to destroy to build a bridge for the Master in return for a keystone.

The Doctor sends out a pulse which severs the link between the soldiers and their masks, sending the masks scuttling away. Corporal Palmer sees to the wounded, but Dodson dies despite Mears having ordered non-lethal force. The Doctor, the Brigadier, Mears and Veronica find that Prodigal has replaced the TARDIS interior with raw vortex energy through which she has sent Tegan and Turlough. She tells them that the Master is behind a sort of mask and, after the Brigadier shoots Mears due to his first initial paired with his surname is an anagram of "Master", the Doctor realises that the Brigadier is actually the Master. He unmasks himself.

Part three
to be added

Part four
to be added

Part five
to be added

Part six
to be added

Cast

 * The Doctor - Peter Davison
 * Tegan Jovanka - Janet Fielding
 * Turlough - Mark Strickson
 * Kamelion / Brigadier Lethbridge-Stewart / The Master - Jon Culshaw
 * Prodigal - Juliet Aubrey
 * Veronica Holmes - Lucy Fleming
 * Captain Edward Mears - Oscar Pearce
 * Sergeant Janet Wharry - Fiona Hampton
 * Corporal Vikram Palmer - Homer Todiwala
 * Dodson / The Autons - Glen McCready

Uncredited cast

 * Auton Doctor - Peter Davison
 * Peri Brown - Nicola Bryant

Crew

 * Cover Art - Ryan Aplin
 * Director - Ken Bentley
 * Executive Producers - Nicholas Briggs and Jason Haigh-Ellery
 * Music - Howard Carter
 * Producer - David Richardson
 * Script Editor - John Dorney
 * Sound Design - Lee Adams
 * Writer - Tim Foley
 * Brigadier Lethbridge-Stewart © Hamish & Lincoln, with thanks to Hannah Haisman and Candy Jar
 * Autons created by Robert Holmes

Continuity

 * The Brigadier is still officially retired from UNIT. (TV: Mawdryn Undead, The Five Doctors, Battlefield)
 * The TARDIS is still being drawn to the middle of the universe. (TV: Frontios)
 * "The Brigadier" refers to Charles Crichton. (TV: The Five Doctors)
 * The Doctor refers to the Gravis. (TV: Frontios)
 * Tegan believes the Doctor is still missing the Sonic Screwdriver. (TV: The Visitation)
 * UNIT had previously served as security for peace conferences in TV: The Mind of Evil and Day of the Daleks.
 * Turlough is embarrassed about the idea of driving in the Brigadier's presence, with the Brigadier still upset with him for crashing his own car. (TV: Mawdryn Undead)
 * The Doctor reminds Turlough that the Brigadier taught him at Brendon Public School. (TV: Mawdryn Undead)
 * Captain Mears refers to London being invaded by the Yeti, (TV: The Web of Fear) dinosaurs (TV: Invasion of the Dinsaurs) and the Loch Ness Monster. (TV: Terror of the Zygons)
 * The Master previously formed an alliance with the Autons and he disguises his TARDIS as a circus tent, which the Doctor picks up as a hint. (TV: Terror of the Autons) He reacquainted with them in the Death Zone on Gallifrey. (TV: The Five Doctors)
 * The Doctor wonders if the military is being run by Rowlands (TV: Terror of the Autons) and Horatio Chinn. (TV: The Claws of Axos)
 * The Master doubts he would become a woman. Later in his timeline, he would regenerate into his Missy incarnation. (TV: Deep Breath, et al)
 * The earlier Doctor has just encountered the Cybermen on Telos (AUDIO: Secrets of Telos) and the Ice Warriors. (AUDIO: God of War)
 * Tegan recalls the Tomb of Rassilon. (TV: The Five Doctors)
 * The Brigadier's memories of the Tomb of Rassilon are vague. Turlough theorises that the Time Scoop bringing the Doctor's companions out of their timeline had affected their memories. (TV: The Five Doctors, School Reunion)
 * Turlough tells the Brigadier about his alliance with the Black Guardian. (TV: Mawdryn Undead to Enlightenment; AUDIO: Gardens of the Dead)
 * The earlier Doctor remembers Tegan and Nyssa telling him about Adric's death, an event in his personal future. (TV: Earthshock, AUDIO: Secrets of Telos)
 * Tegan recalls the Doctor feeling the effects of his past incarnations being taken out of time by the Time Scoop. (TV: The Five Doctors)
 * The Brigadier was unaware that Turlough was from another planet. (TV: Mawdryn Undead, Planet of Fire)
 * The Brigadier remembers capturing the Master once (TV: The Dæmons) before he escaped. (TV: The Time Monster)
 * Whilst reading Tegan's mind, Prodigal sees the day she met the Doctor on the day her aunt Vanessa died (TV: Logopolis) and encountering the Cybermen (TV: Earthshock, The Five Doctors; AUDIO: Secrets of Telos, Conversion)
 * The Master refers to the Martian Pyramids. (TV: Pyramids of Mars)
 * The Doctor hopes the Brigadier doesn't end up on Nerva Beacon. (TV: The Ark in Space, Revenge of the Cybermen)
 * The future Doctor still has possession of the Seal of Rassilon, which his third incarnation took from the Master in the Death Zone. (TV: The Five Doctors)
 * The TARDIS previously became an empty shell in TV: The Wheel in Space and will do so again in(TV: Father's Day.
 * The Doctor refers to the Brigadier as "the original, you might say." (TV: The Five Doctors, The Doctor Falls, Twice Upon a Time)
 * The Doctor refers to the Arc of Infinity. (TV: Arc of Infinity)
 * Tegan recalls Nyssa collapsing after leaving the Urbankan ship. (TV: Four to Doomsday)