Gavin's Death — Gillian Larkin

Cara Daniels has a secret job. She saves the lives of people who are going to be murdered. She also saves the souls of the people who are due to commit the murder.
In book 4, Gavin Bennett is in danger of being murdered.
Gavin works at an estate agent's, and within five minutes of seeing him at work, Cara can well believe that many people could hold a grudge against him.
The problem is that Cara has to work out who hates Gavin enough to kill him. And then she has to stop that from happening.