Reverse Engineering (audio story)

Reverse Engineering was the second story in the audio anthology Purity Undreamed, produced by Big Finish Productions. It was written by Jonathan Morris and featured Colin Baker as the Sixth Doctor, Bonnie Langford as Melanie Bush, Ruth Madeley as Hebe Harrison and Imogen Stubbs as Patricia McBride.

Publisher's summary
When Patricia is invited to a secretive Swedish clinic by an old colleague, she tips off the Doctor, Mel and Hebe, who go undercover to investigate. Charismatic geneticist Killian Holm offers to restore youth to his wealthy patients, but the truth of his work is far more radical - and far more dangerous!

As an ancient horror reforms beneath the clinic, the Doctor must race to save humanity from an unspeakable temporal disaster.

Part one
Patricia is invited to the Emit Institute in Sweden by Killian Holm. Whilst waiting for a demonstration, she is surprised to see Mel, who has been working at the institute for two weeks but has come to see her slightly too early; she tells Patricia that, in a few minutes, she will see something strange and must contact the Doctor through Hebe. Patricia is shown a group of cloned Neanderthals and offered the chance to study them. When Holm is called away, she calls Hebe, who appears almost instantaneously.

Holm meets the Doctor and Hebe, calling themselves Dr Solace and Jane Bond and pretend not to recognise Patricia when she joins them. They are given a tour and learn that the clinic offers to restore youth, but the Doctor finds the presentation to be full of meaningless technobabble and wonders how it is really done. He signs up for the treatment and, later, goes with Hebe to meet up with Mel, who informs them that the institute's profits are funding secret research in the lower level. Having stolen Tarek Gamal's passcard, she takes them downstairs and they find a machine that causes time to travel in reverse.

Patricia goes for dinner with Holm, but he has to leave on a matter of security. He and Tarek find the Doctor, Mel and Hebe and has them locked in their room. Patricia rescues them and they head to the TARDIS in a maintenance storeroom where the Doctor collects a device which detects a dangerous amount of temporal distortion. Patricia tells them about the Neanderthals and, after the Doctor disables the camera systems and mechanic locks, heads to the laboratory with Mel.

The Doctor examines Holm's time machine and finds that it is not responsible for the distortion. He and Hebe find the remains of a crashed spaceship, generating a repair field which Holm is exploiting and which reconstitutes the body of the alien pilot. Meanwhile, Mel and Patricia are caught by Holm and Tarek and learn that Holm has bred what he calls the "perfect homo sapiens". Unless Patricia tells him who she is working for, Holm will age Mel to death.

Part two
The reversion machine loses power and Mel claims that Tarek is working with her and Patricia, distracting Holm and giving Patricia the opportunity to knock Tarek down and steal his gun. She destroys the machine and they escape when the security systems come back online, Holm and Tarek being locked in behind them. They are soon caught by guards, but manage to evade them when metal struts start rising through the floor as the spaceship reconstitutes itself.

The Doctor identifies the pilot as a Soloch, whose kind enslaved most of the Sixth Galaxy before erasing themselves with a grandfather paradox. Upon learning that the machine has been damaged, he goes with Patricia to repair it whilst Mel and Hebe evacuate everybody into the TARDIS and encounter Holm's savage homo sapiens and the Neanderthals, who save them.

The Doctor repairs the machine and the Soloch is restored, ageing Holm to death and chasing the Doctor whilst Patricia escapes. The Doctor and Patricia manage to get to the TARDIS and Tarek tries to shoot and kill the Soloch, but he becomes trapped in a time eddy and the Doctor only just manages to save him. The TARDIS dematerialises and the facility is destroyed by the release of the reversion machine's radiation causing the ship to explode again. Tarek has no memory of the last two years, having been made younger.

After taking the Emit staff to Stockholm, their memories lost, Patricia expresses her interest in Holm's research, which has been completely destroyed. The Doctor, Mel and Hebe offer to take Patricia back to Sheffield in the TARDIS, which she accepts on the condition that she be taken to travel in time first. The Doctor asks her if she would like to go to the past or future; she answers that she wants to see the shape of things to come.

Cast

 * The Doctor - Colin Baker
 * Mel Bush - Bonnie Langford
 * Hebe Harrison - Ruth Madeley
 * Patricia McBride - Imogen Stubbs
 * Killian Holm - Stephen Riddle
 * Tarek Gamal - Homer Todiwala

Worldbuilding

 * Holm offers Patricia tea or coffee.
 * Patricia does not like milk in her coffee. In university, she told Holm that she liked it as black as possible.
 * Mel has been working as an analyst in the computer department.
 * Neanderthals lived over forty-thousand years ago.
 * Tarek is Head of Data Security.
 * Hebe introduces herself as "Bond, Jane Bond".
 * Spaceships in the Sixth Galaxy use repair fields to reverse time if they are damaged.
 * Patricia has not been clay pigeon shooting for some time.
 * Hebe says "what the hake are they?"

Continuity

 * The Doctor says that he would allow his appearance to be changed over his dead body. (TV: The Tenth Planet, etc.)
 * Mention is made of the groundwork laid by Whitaker and Kerensky in their efforts at time technology. (TV: Invasion of the Dinosaurs, City of Death)
 * It has been three months since "the Mindless business". (AUDIO: The Mindless Ones)
 * The Doctor once again demonstrates an ability to move against a conflicting current of temporal energy. (TV: Invasion of the Dinosaurs)
 * The Emit Institute is besieged by a time storm and its surrounding eddies. (TV: Dragonfire, The Three Doctors)