I'd really give this one 3.5 stars (B-). The book centers on the murder of a US Senator whose body is discovered by his chief of staff, Nick Cappuano. The detective in charge of the investigation, Sam Holland, is a woman with whom Nick had a one night stand six years before. The two never forgot one another, and thankfully the reason for them not staying in contact after their night together gets cleared up early in the story.On the positive side, I liked both lead characters and the story flowed really well. The victim and some of the people around him seem to lead quite complicated lives and as the author reveals layer after layer of information, the pacing works quite well. Nick seems like a genuinely nice and smart guy, while the portrayal of Sam as a good detective in need of redemption manages to be effective rather than eyeroll-inducing.While I thought Sam and Nick built a good relationship, the investigating officer-witness/possible suspect angle brings up some ethical issues that didn't get dealt with as effectively as they needed to be. Sam and Nick get quite heavily involved while the investigation is still open, and it just didn't ring true that other officers would let this slide quite as much as they do in Fatal Affair. Because I liked the characters and I was enjoying this thrill ride of a story, I could move past this issue somewhat, but my other problem frustrated me more.I could buy that Nick would feel protective of the woman he loves, but Sam is an experienced DC detective. Nick's interference with her doing her job and his involvement in job discussions with her superiors drove me absolutely batty. This incidents aren't a constant distraction, but they did happen often enough to pull me out of the story a couple of times. Even so, I did enjoy Fatal Affair overall and I plan to read more in the series.