Had all the elements I love in a romance; tortured hero, capable heroine, smart dialogue, denial or unwillingness to act on lust. Yet somehow it fell a little flat for me. I never got emotionally invested in either one. Maybe it was because the overall tone of the book was too light-hearted given the suffering Sin had experienced. There were some very funny scenes and exchanges between Callie and Sin that would immediately be followed by a few pages of Sin recalling past atrocities and reasons why he was unworthy or incapable of love. Too jarring a transition and it kept me from fully engaging in either the angst or humor.