Midnight Blues (Darkyn #6.5)
Samantha and her mate Rafael are homicide cop. Once they were ordered to investigate the case of the cops lying at convent. This corpse was a message for one of the woman inside the convent, Daniela, or Cristál.
Her old nemesis, Donatien, a Kyn gone bad centuries ago, wants her for her powers to heal. He loves torturing people, and she can make them last longer. For years she has run from him, but always he finds her.