Purgatory 12 (audio story)

 was the first story in the ninth series of The Fourth Doctor Adventures, produced by Big Finish Productions. It was written by Marc Platt and featured Tom Baker as the Fourth Doctor, Lalla Ward as Romana II, Matthew Waterhouse as Adric and John Leeson as K9 Mark II.

Publisher's summary
Still searching for a way out of E-Space, the TARDIS crew land on an isolated space rock... and immediately find it drawn towards a nearby asteroid.

The asteroid has air and gravity unequal to its size and is strewn with the wrecks of spaceships. Veins and pools of rust are everywhere.

Stuck on the asteroid away from his friends, Adric discovers that it's a penal colony housing a gang of alien convicts - but resources are low, and they're starting to starve.

But escaping the prisoners is only the first part of the traveller's troubles. Because there's a sinister presence at the heart of the asteroid... and it won't release them quite as easily.

Part one
to be added

Part two
to be added

Part three
to be added

Part four
to be added

Cast

 * The Doctor - Tom Baker
 * Romana - Lalla Ward
 * Adric - Matthew Waterhouse
 * K9 - John Leeson
 * Scraya / Pips - Amy Downham
 * Mang / Wunshooz - Liam Fox
 * Colonel Aesillor Zyre - Nimmy March
 * Crimsson - George Watkins

Worldbuilding
to be added

Continuity

 * The Doctor mentions Alzarian river fruit. (TV: Full Circle)
 * Adric is mourning the death of Varsh. (TV: Full Circle)
 * The Doctor uses the spare Food machine (AUDIO: The Age of Sutekh)
 * K9 plays chess with Adric. (TV: The Sun Makers, The Androids of Tara)