Mel-evolent (audio story)

 was the second story of the eighth season of Big Finish Productions' Short Trips series.

Publisher's summary
Mirror mirror on the wall, something stalks the TARDIS halls...

A glimpsed reflection in a dark and dusty corner leads Mel on a journey Through The Looking Glass.

Witchcraft and shadows reign.

Mel must face the evil at the heart of it all, while the Doctor battles to save a TARDIS determined to prove it’s not only bigger on the inside, but darker. Much darker.

Plot
The Sixth Doctor is off sulking in the TARDIS's theatre, after yet another attempt by Mel to get him on a proper cycle of diet and exercise. Mel takes the opportunity to look around the wardrobe of the theatre, and discovers a mirror that shows a dark reflection of herself. The Doctor rushes over to investigate and informs her that the mirror is a Space-Time Visualiser, an object that lets the viewer see any event in history.

Suddenly, the TARDIS is filled with noises. Using the Space-Time Visualiser, the Doctor and Mel discover that a horde of goblin-like creatures are ripping out parts of the TARDIS and bringing them into a world within the Space-Time Visualiser. The Doctor quickly dresses Mel up to look like the dark reflection of herself, adding only a set of earrings that will allow him to communicate with her while she's in the other world, and sends her into the world of the Visualiser.

Upon arrival, Mel finds herself in a version of her room in the TARDIS stripped of all personal touches. She wanders the halls of this version of the TARDIS and encounters a group of the goblin-like creatures. Pretending to be the dark reflection of herself, she demands to be taken to their leader. The goblins lead her to a room with a faceless woman, whose appearance is constantly changing.

The Doctor and Mel establish a psychic link with the woman, and find out that the goblin-like creatures are Thrusks; a race that disappeared from the main universe and has become a parasitic Vortex creature. The Doctor and Mel realise that the faceless woman is an ancient Time Lord, infected by the Thrusk and forced into a state of constant regeneration to prevent their expulsion from her body. The duo realise that the Thrusk mean to capture parts of the Doctor's TARDIS and bring them together with parts from Lady Tamira's TARDIS, in order to destroy the universe, and make a new one, using the Thrusk as the building blocks of the new universe.

At this point, the psychic link breaks, and Mel is horrified to discover that her doppelgänger has arrived in the room, with a horde of Thrusk. Mel futilely attempts to trick the Thrusk into believing that she is their true leader, but her doppelgänger is able to break apart her argument. Mel tries a different tactic, and manages to convince the Thrusk that their leader means to destroy them all. Mel's doppelgänger doesn't deny this, much to the chagrin of the Thrusk. As Mel is pulled out of the Space-Time Visualiser, she witnesses the Thrusk attempting to attack Mel's doppelgänger.

Later, Mel awakens in the control room of the real TARDIS, and witnesses the Doctor conversing with Lady Tamira. She thanks the two of them for saving her from the Thrusk and vows to return to her time on Gallifrey, and keep the secrets of the future safe. After she departs, Mel notes with some amusement that Lady Tamira looked exactly like Mel, which the Doctor assures her isn't out of the realm of possibility, before the two depart for their next adventure.

Characters

 * Sixth Doctor
 * Melanie Bush
 * Thrusk
 * Lady Tamira

Worldbuilding

 * Tamira has a Type 2 TARDIS.

Continuity

 * The Doctor notes that Time Lords sometimes regenerate to look like existing people in the universe. (TV: Destiny of the Daleks, The Caves of Androzani, Deep Breath)