I highly recommend Heartsick. 
 ...Yeees! Oh, how i love thee. *evil grin* 
 My fascination with serial killers came back with Heartsick. With a woman as the serial killer made it all the more interesting. I miss watching Dexter. =( 
 Archie and Gretchen have a very complicated relationship. You'd think Archie doesn't want anything to do with her after she abducted, tortured, left him wanting to die, then turn herself over to the police. Chelsea Cain is playing with my emotions, because I felt something for Gretchen other than hate and revulsion. 
 The story was compact. I loved Archie's POV. He knows there's something wrong with him, that his life sucked, and his mixed feelings for Gretchen were abnormal. Still, he does a good job being a cop. But the darkness Gretchen showed him during his time with her remained. 
 Susan the reporter is okay, too. Her life is as f*cked up as Archie's, but she hides it well. The way Gretchen read her like an open book whe she visited at the prison is so enjoyable. Hee. 
 I am in love with how Gretchen's mind works! Manipulative, smart, and very, very devious. This is the villain to beat! 
 Heartsick has gore, horror, and pain. I had an unbelievably good time reading it! It takes one to know one, right? So in order for Archie to defeat Gretchen once and for all, he has to think and act like her. like a maniac. :)