The Lillian Rayne Trilogy: Book 3. The Lillian Rayne Trilogy, #3

Lillian losing her memory makes everything more complicated. The world of vampires and hunters that she used to know is foreign to her. She has to cope with losing her memory, all while trying to figure out who she can and cannot trust. Lillian struggles to find her place, as she works to remember who she once was. Eleanor, her enemy half-sister, becomes a growing threat to Lillian and the people she loves.
Lillian learns that one of the people who claims to be close to her is working with Eleanor. Lillian has to find a way to defeat Eleanor, before Eleanor gets to her first.