If someone is thinking that the series is ending in the trilogy then this sort of thinking is incorrect. Lara Adrian never had the mood to end the series at the third part because the author is not taking the series to the next part in a sequence. Even if someone tries to skip a few parts then there would be no issue at all because the story would be easily understandable.
Every part plays the role of an individual novel as well. Claimed in Shadows and Born of Darkness gives a clear indication that the story is not going to have an episodic plot. The author wanted to provide the narrator luxury to choose the episode of his choice. It made the narration difficult for Hillary Huber at some stages but the narrator tackled everything brilliantly.
Elise is with a psychic gift in this episode and she is looking for vengeance against the vampire world. One way or the other, she is going to kill every vampire that is present on the face of the world. It is her psychic powers that lead her to vampires but those powers are also eating her up from the inside. She needs serious help to get the job done and for this, she goes to Tegan who knows a lot about her pain.
Tegan also wants to get rid of the rogue vampires so he forms a team with Elise which is not allowed in his world. The two form a forbidden bond for the sake of vengeance at the beginning and then they start loving each other which proves to be deadly for both of them.