Lord John and the Hand of Devils - Diana Gabaldon (Outlander companion short stories collection). Includes "Lord John and the Hellfire Club", "Lord John and the Succubus" and "Lord John and the haunted soldier"
Tasmin was killed on her birthday. A psychology degree, a mother who pushed her to greatness, and a future anyone would die for. But then her murderer saved her life, only to sell her into a totally different existence.