Suzanne Brockmann 
Love with the Proper Stranger [EPUB ebook] 

An undercover agent risks his cover when he falls in love while tracking a serial murderer in this romantic suspense from a New York Times bestseller.FBI agent John Miller is on the trail of a notorious female serial killer, and he can’t blow his cover to anyone. Not even the beguiling Mariah Carver, who unwittingly entangles herself in a web of deadly deceit.John can’t deny that sweet, sensual Mariah is the woman he’s been waiting for, but he can’t act on the passion that he feels for her. He’s poised to wed the woman suspected of being the ruthless Black Widow, who marries-then murders-her victims.