Diana Rowland is a one of the few rare authors who didn't allow herself to stagnate. It takes balls to turn everything you've learnt on its head, and the only other author I know who did such thing was Karen Marie Moning with her Fever series.
The successful summoning in the end of Sins of The Demon brings Kara to demons realm, and all the next book she spends there re-learning and re-evaluating everything she knows. It's daring and awesome and strongly reminds me of World of Warcraft with its computer game-like sense of reality. The reader's emotions go through a roller coaster along with the main heroine's. Characters come and go, some stay your friends, others become your enemies... and some others blow your mind and just click as something right.
I loved that Kara had that. I loved that she found a new strength in her abilities and her new circumstances. She didn't break, she didn't wallow in her sorrows, she just got very angry and kicked ass. Anyway, I wholly recommend this series and can't wait to read the next instalment which comes out this month. Read this.