Bernice Summerfield was not a television Doctor Who companion but was introduced in post-1989 novels, and has had a range of her own Big Finish audios some of which have featured Doctor Who television monsters. She has appeared as the Doctor's companion in a few Big Finish monthly Doctor Who audios. For those that have not followed her range, this story might be a good place to start.
The Companion Chronicle range is occasionally brilliant. Three things need to be in place. Appropriate Doctor Who companions, a decent/clever/fresh story and a suitable story pace to engage the listener when there is mostly only one narrative voice. The story is in keeping with other Big Finish featuring Bernice Summerfield, but is a far cry from anything 1987-1989 and more in keeping with the evolution of the post 1989 Doctor and events. Lisa Bowerman is a good narrator playing a likeable character and one builds up a good mental picture of the seventh Doctor at times. The plot is good with two separate story threads (Summerfield's being the heavier) joining in the second episode for quite a climax as it is a very strong and memorable idea.
I always go into seventh Doctor stories with some apprehension but have to say that this story had me growing my interest throughout and I was captivated towards the end even on just one listen. Some stories take a relisten to an episode to follow events fully (The Suffering), and the occasional one, after 3-4 listens (The Drowned World) I have just lost interest. This story gets so good when it is running out of time; it is a huge risk writing/editing a story this way, but I actually feel on this occasion it pays off.