Loved both Zane and Tessa as characters even though both are flawed—but they are aware God is working on parts of their lives and they try to be humble about that, so they feel very real to the reader. We've had them as side characters for the rest of the series and I was definitely ready to get to the bottom of their story.
The suspense story of the book is based on having to protect to President when he comes to town for a visit to a private estate. They have to sort through garden variety threats to figure out which ones are real and which aren't, and the clues for the real one are very subtle indeed. It definitely kept me flipping pages as time ran out before the visit!