Survival of the Fittest (audio story)

Publisher's summary
The hive of the Vrill bears the scars of a terrifying cataclysm. Only a handful remain alive, hatched after the holocaust of the mysterious Winterlack. The Vrill seek a new Authority. They find the Doctor, a two-legged creature who can lead them to survival. He must solve the mystery of the Carrion beast that haunts the lower chambers. He must face the Winterlack that still stalk the mountains. And he must find a path that does not lead to extinction...

Cast

 * The Doctor - Sylvester McCoy
 * Elizabeth Klein - Tracey Childs
 * Steffen - Adrian Bower
 * Rose - Hannah Smith
 * Lilly - Evie Dawnay
 * Jackson - Mark Donovan
 * The Carrion - Alex Mallinson
 * Butterfly - Rupert Wickham

Continuity

 * There no longer seems to be a spare TARDIS key in the cubbyhole above the "P" outside the TARDIS. (BFA: The Architects of History) It would be restored by the time of the Doctor's regeneration into his eighth incarnation. (DW: Doctor Who)
 * The removal of Klein from the timeline in BFA: The Architects of History probably resulted in the events of this story being either changed significantly or prevented entirely. The Doctor may have visited the Vrill homeworld alone or with another companion, but his/their adventure would certainly have ended quite differently.

Timeline

 * Survival of the Fittest occurs after BFA: Klein's Story
 * Survival of the Fittest occurs before BFA: The Architects of History