This is the conclusion to the "Leela Trilogy" within the Companion Chronicles, and it follows the same general format that was used for "The Catalyst" and "Empathy Games". Set late in Season 15, at least in terms of the main story, the primary goal is to explain the framing device of the entire trilogy and bring Leela's story to a conclusion.
The most obtuse and irritating part of the first two stories in the trilogy was the framing device, so the fact that this audiodrama focuses so much upon it is a bit of a problem. Unfortunately, it's just the beginning. The entire story involves several characters moving through time out of order, so conversations are often confusing and hard to place in context, even after everything is explained. And because this is one of the Companion Chronicles, and most of the voices are done by Louise Jameson herself, it can be utterly baffling.
Adding to the confusion (and aggravation) is the presence of K-9. Not only is time spent trying to work this story into K-9's continuity, but his behavior is bizarre due to some reprogramming along the way. It just adds to the elusiveness of the plot. Once the titular "time vampire" arrives on the scene, towards the climax of the story, it becomes almost impossible to figure out just what is going on.
It does manage to bring Leela's story to something of a conclusion, far better than "The Invasion of Time" does, but it does so in a way that just isn't very clear. In fact, I'm not even sure that I know how her story really ends. Perhaps that was the intent, but if so, it still strikes me as a story that would have worked better on television, where the visuals could clarify what audio cannot.