The Prisoner's Dilemma (audio story)

Publisher's summary
Two prisoners meet in a prison cell. Zara is searching for the segments of the Key to Time; she was only born yesterday but already she’s killed hundreds of people. Ace is more ambitious: she was going to kill everyone on the planet.

What have they got against the people of Erratoon? They go peaceably about their simple assignments, beneath their artificial sky. They share their meals and leisure time and they never ask questions. Are they even real?

Ace and Zara will only survive if they can trust each other. Or perhaps if they sell each other out... If not their awful punishment is to become just like everyone else.

Cast

 * Ace - Sophie Aldred
 * Zara - Laura Doddington

Continuity

 * Ace mentions meeting "a man made from liquorice." (TV: The Happiness Patrol)
 * Ace mentions having Christmas dinner in Cheldon Bonniface in 1992. (PROSE: Timewyrm: Revelation)
 * Zara is the twin sister of the Fifth Doctor's former companion Amy (later Abby). The Doctor previously encountered Zara on Mars in the distant past (AUDIO: The Judgement of Isskar) and on Chaos at the end of recorded time (AUDIO: The Chaos Pool). Both of these events have yet to take place in her personal timeline.
 * Ace remembers travelling with the Doctor and a woman wearing earrings. (PROSE: Love and War)