The next full length novel, due out in January, will be the last in the Cat and Bones series. The author explains why: http://jeanienefrost.com/2013/08/the-grave-stops-here/ Part of the explanation is that one of the projected book's worth of plot arc was included in this novella.
Bones has a birthday. Annette is attacked and there's some confusion about who attacked her, altho it is clear that Ian found her post attack. Annette says it was not Wraith, who is supposedly Bones' half brother, and was going to be her birthday present to Bones. Antics ensue.
Frost does some amazing stuff in this novella; it's some of the cleverest world building I've encountered in a while. Demons aren't supposed to be able to possess vampires in this world, but there's an exception, and it is so tightly constrained I wouldn't expect to have it come up again. The demon possession of multiple people at once offers the opportunity for all kinds of betrayal/loyalty conflict -- tons of fun. Best of all is how Ian turns out to be immune. And, of course, how they get additional demon bone to threaten other demons with.
It always kind of bugs me when people who are way old nevertheless seem excited by/participate in much more recent traditions (green bean casserole and candied yams, in this case), but I understand why authors do this. It was a fun romp, and of course I'll read the final entry when it comes out.