Robert B. Parker 
Crimson Joy (A Spenser Mystery) [EPUB ebook] 

Private detective Spenser is on the case of a serial killer with an unusual calling card – he leaves a red rose on the body of each of his victims. And when the madman targets Spenser’s girlfriend Susan Silverman, his resolve is strengthened and he determines to find the murderer – no matter what the risk.’One of the great series in the history of the American detective story’ New York Times