Day of the Master (audio story)

 was the third and final story in the audio anthology Ravenous 4, produced by Big Finish Productions.

As well as bringing together multiple incarnations of the Master, this story both explained and depicted the genesis of the Ravenous, inadvertently caused by the ancient Time Lord engineer Artron, as well as their end, by Artron's own command, as he returns them to their Kolstani forms.

By visiting Artron around the time of his discovery of artron energy, and before the start of the Rassilon Era, this story depicts Time Lord history at an early point in their history along with Collision Course, which featured the first prototype TARDIS while this one features a fleet of battle TARDISes placing it afterwards.

Liv Chenka and all others within the same time zone temporarily gain the ability to regenerate, like Time Lords, but indefinitely, and without changing form. The man who granted Helen's wish in Fairytale of Salzburg is also revealed to have been Artron.

With regards to the Master's timeline, Day of the Master finally explains how the maniacal Time Lord's twelfth and final regeneration,, managed to acquire a new regeneration cycle. Three incarnations of the Master watch as he regenerates into.

The Eleven is also depicted regenerating into his next form, the Twelve, after sustaining killing blows from all three Masters.

Publisher's summary
The Doctor investigates a mystery in the vortex, Liv follows the trail of their enemy, and Helen searches for a god. Everywhere they go there is a Master or Mistress, but is the Doctor's oldest enemy there to hinder them, or to help? With the TARDIS crew scattered and lost, only a miracle can save the universe. And for that to happen someone is going to have to die.

Plot
to be added

Cast

 * The Doctor - Paul McGann
 * Liv - Nicola Walker
 * Helen - Hattie Morahan
 * The Eleven - Mark Bonnar
 * The Master - Eric Roberts, Derek Jacobi and Geoffrey Beevers
 * - Michelle Gomez
 * Ravenous 1 / Kolstani 1 - George Asprey
 * Ravenous 2 / Kolstani 2 / Valcon - Susie Emmett
 * Artron / Cadrin - Robert Whitelock

Continuity

 * The Doctor notes that and  have worked together in the past. (TV: The Mark of the Rani)
 * River Song once teasingly mistook Missy for the Rani. (AUDIO: The Bekdel Test)
 * The Crucible of Souls is used by the Ravenous and the Eleven in their grand plan. The Crucible was previously a part of a plan by the Nine and the Doom Coalition. (AUDIO: The Crucible of Souls)
 * The "War" Master is granting his past self a new regeneration cycle as part of a deal with the CIA. (AUDIO: The Devil You Know)
 * The "War" Master declares that his past self would have "a new body, at last". (TV: The Keeper of Traken)
 * Missy says "Hello you" to the "Bald" Master. (AUDIO: Dominion)