Blood Bonds (Otherworld, #21)

They're the D'Artigo sisters: savvy half-human, half-Fae agents of the Otherworld Intelligence Agency. Camille is the Queen of Dusk and Twilight. Delilah is a two-faced werecat and the Autumn Lord's only living Death Maiden. And Menolly is a vampire princess and married to a gorgeous werepuma Amazon. It's been four long years since they first found out about Shadow Wing. . . and now, they're facing the end of the line. It's time for the D'Artigo sisters to extinguish Shadow Wing's evil forever, before he goes mad and tries to unravel the world. . .

This is the last book--#21--in the series.