Past Lives (audio story)

 was the first story in the Once and Future audio series, produced by Big Finish Productions. It was written by Robert Valentine and featured Tom Baker as the Fourth Doctor, Sadie Miller as Sarah Jane Smith, Jemma Redgrave as Kate Stewart, Ingrid Oliver as Petronella Osgood and Rufus Hound as.

Publisher's summary
The Time War. The Doctor has been injured and brought to a Time Lord field hospital. His body glows with energy, but this is no regeneration into a future form – instead, the Doctor's past faces begin to appear as he flits haphazardly between incarnations...

Staggering to his TARDIS, the Doctor sets out to solve the mystery of his 'degeneration'. Who has done this to him? How? And why? From the Earth to the stars, across an array of familiar times and places, he follows clues to retrace his steps, encountering old friends and enemies along the way. Tumbling through his lives, the Doctor must stop his degeneration before he loses himself completely...

Settling as his Fourth incarnation, the Doctor goes in search of the Monk, with a vague memory that he had something to do with his 'degeneration'.

On Earth, the Monk is meddling, bringing Sarah Jane Smith to the future UNIT HQ to steal a device for an alien race. The Doctor must help Kate Stewart and Osgood foil an invasion before he can confront the Monk about what he knows…

Plot
During the Time War, the Doctor biogenically reverts through their incarnations and runs to the TARDIS, finally stabilising in their fourth incarnation in part due to the ship's calming influence. He uses a temporal iterator to trace the Monk to an island off the coast of Scotland in the 20th century, remembering that he has some involvement with what is happening, and follows him to 22nd century Hong Kong.

to be completed

Cast

 * The Doctor - Tom Baker
 * Sarah Jane Smith - Sadie Miller
 * Kate Stewart - Jemma Redgrave
 * Osgood - Ingrid Oliver
 * The Monk - Rufus Hound
 * "Mr Mallory" / Galavant / Baravoar - Ewan Bailey
 * Field Surgeon / Black Market Merchant - Dan Starkey
 * First Doctor - Stephen Noonan
 * Second Doctor - Michael Troughton
 * Third Doctor - Tim Treloar
 * Fifth Doctor - Peter Davison
 * Sixth Doctor - Colin Baker
 * Seventh Doctor - Sylvester McCoy

Continuity

 * Sarah had just left the Fourth Doctor moments earlier when she confronts the Monk. (TV: The Hand of Fear)
 * The Monk has put the money he had stolen into a Swiss bank account. (TV: The Time Meddler)
 * Sarah has met the Monk before. (AUDIO: How to Win Planets and Influence People)
 * The Doctor admires the celery on Osgood's jacket. (TV: Castrovalva, et al)
 * The Monk is aware that the Doctor will have a daughter, much to the Doctor and Sarah's surprise. (TV: The Doctor's Daughter)