(Warning: Significant spoilers follow!)
This is the last Big Finish audio story to feature actress Caroline John, who died a few months ago (sadly becoming one of four major Who actors to die in the last two years). John played the character of Liz Shaw in a mere four stories at the start of the Third Doctor’s era. Despite appearing in so few tales, the character remained popular, and has been in several Big Finish audios, as well as other bits of spinoff fiction.
This final story takes the form of a series of letters being sent back and forth between Shaw and her mother (Rowena Cooper). These letters make references to most of the TV stories Shaw appeared in, and the final part seems to take place just before her last TV story, “Inferno”.
In this story, people have been receiving letters saying something to the effect of