I didn't care for this book at all. The beginning was boring. The two main characters spent a lot of time second guessing themselves and that got old fast, plus their past kept being mentioned or thought about over and over when once would have been enough to clue the readers in on what had happened. The dialogue seemed stilted and didn't flow, especially between Aiden and Nia.
Finally, the main guy, Aiden, had a serious football injury, yet he was able to join the army and his bum knee gave out during a search in a foreign country and one of his friends was killed. No military service would have accepted the guy with a serious knee injury, so that alone raised questions on everything else in the book as to accuracy.
This may be fiction, but we do like accuracy such as search and rescue techniques, police techniques, FBI techniques, etc.