Secret Investigation by Elizabeth Heiter is a fast-paced suspense novel. It is the second novel in the Tactical Crime Division series. Each book in this exciting series can be read on its own. This novel has strong characters and plenty of action. Romance does develop between our primary characters and I like that it builds slowly. I appreciated that there were not passionate love scenes (I am not into intimate scenes in books). I like the suspense and danger in this story. I find it intriguing. Readers will enjoy trying to identity of the bad guy (depending on your sleuthing level on how soon you figure out this whodunit). I liked that there was more to the mystery than just defective armor. There is danger, suspense, romance, and action in this intriguing tale. I found Secret Investigation to be a captivating story that was over far too soon. Secret Investigation will have you quickly turning the pages to see what happens next.