It certainly wasn't a problem with the script as such: this is a far better story than either The Nightmare Fair or Mission to Magnus. It rapidly becomes apparent that the medieval village where the Doctor and Peri arrive is not what it seems, but I was still surprised and gratified by the plot twist at the end of the first disc, and though that in itself sets up the eventual resolution rather inevitably, it is all very well done.
I hope now that the other Lost Stories of this run will be as strong as Leviathan. I don't really envy Big Finish, lumbered with the two well-known but really awful stories as part of the project, and having to decide where to put them in serquence. It was rather brave to front-load the Lost Stories as they did. In their place, I would have tried to conceal them in the middle somewhere.
Returning to the main sequence of Big Finish stories, Andy Lane has delivered another hit with A Thousand Tiny Wings, where the Seventh Doctor visits Kenya in the midst of the Mau Mau crisis of the 1950s and runs into Dr Elisabeth Klein, last seen in Colditz during the second world war trying to make sure that the Germans won (and aided by a sinister guard called Kurtz, played by one David Tennant). The story turns out to be a fairly standard Who plot, but the execution is excellent - both the African soundscape and the white women cooped up in a remote farmhouse waiting for the inevitable doom to arrive. (The incidental fact that I have passed through Kenya several times recently made it seem a bit more personal.) It sounds as if Lisa Bowerman as director was able to get the best out of her cast and team.
Alas, Bowerman is less well served in the latest Companion Chronicle, Bernice Summerfield and the Criminal Code, a two-hander between her and Charley Hayes (who has I think the unusual distinction of having appeared on Doctor Who in the form of a bump in her mother's tummy, visible to the careful observer of Wendy Padbury's cameo in The Five Doctors). Unfortunately the plot is slow to get going, has the Seventh Doctor rather uncharacteristically taking a public role as a mediator, depends rather heavily on a particular interpretation of what the Tardis translation circuits actually do, and then packs far too much exposition of What The Story Was Actually About into the last three minutes. The crew express the hope in the extra tracks that this will attract more listeners to the Bernice Summerfield range, but I'm inclined to doubt it.
I want to generalise from this to a wider gripe from a Companion Chronicle subscriber. I loved the idea of bringing back companions of the first four Doctors to tell their own stories. It seemed however a bit odd to start bringing in Fifth, Sixth and Seventh Doctor companions, and now we have crossed another line in bringing in a companion who was never seen on TV at all. I don't really approve.
On the other hand, those who don't know the Bernice Summerfield audio stories, but who download the free podcast of "Making Myths" (a short story from the years old Buried Treasures CD, starring Lisa Bowerman as ever with Sarah Mowat as a hamster-like alien journalist) will be charmed by it. Indeed, this would have been a rather better two-hander for the Companion Chronicles series, except that it came out several years too early.
In summary, A Thousand Tiny Wings and Leviathan are both very good; Buried Treasures: Making Myths is enjoyable; and you can skip Bernice Summerfield and the Criminal Code.