Fifth Grave Past the Light. Number 5 in series

Charley Davidson may not look like your everyday, run-of-the-mill grim reaper, but she has vowed to reap grimness wherever she goes despite this unfortunate fact. Sadly, she gets sidetracked when the sexy, sultry son of Satan, Reyes Farrow, moves in next door. As he is the main suspect in her arson case, she has vowed to stay away from him until she can find out the truth. However, when dead women start appearing in her apartment - lost, confused and terrified beyond reason - Charley has no choice but to ask for Reyes's help, especially when it becomes apparent that her own sister Gemma is the serial killer's next target.
With his ability to observe incorporeally, surely he can find out who's responsible. And even if he can't, he is the one man alive who could protect Gemma no matter who or what came at her. But he wants something in return: Charley. All of her - body and soul. And to keep her sister safe, it is a price she might be willing to pay .