Doing a hitchhikers guide to the Galaxy here and stretching the definition of trilogy to breaking point!
This starts out as a story of the marriage between Marcus, Matthew‘s son from the trilogy and Phoebe, Diana‘s friend. At least initially the stakes seem to be much lower and this is large of domestic drama.
(Later…)
And indeed, this is how the book continues, very much as a comfort read after the stressful and significant events of the trilogy. We learn more of the backstory of Marcus and the events leading up to the massacre in New Orleans, but of course we readers already know the outcome of this. A further story thread is Phoebe’s experience of becoming a vampire, which does include minor peril but does introduce us to much more information about the life and habits of vampires in this universe. Finally, we have the story of the twins, Rebecca and Philip as they become toddlers and grow into their new powers. There’s no major stresses here either, other than something of a conflict (inevitably) with Baldwin.
So, yes, I did enjoy this. It was an interesting read and did serve to expand on the world of all souls but really only works as the fourth book in the trilogy, had I read it standalone I probably would have been disappointed in the lack of actual incident .
It will be interesting to see where Deborah takes these characters in the fifth book.