Vendetta. Jim Nash Adventures, #9

Nash turns himself into an insurance investigator tasked with discovering whether the death of a former drug dealer is cause for concern regarding a life insurance payout. The policy can't be paid until Nash has finished his investigation into the old man's former life. Along the way, Jim somehow manages to fall in love with the pretty and personable beneficiary. Secrets and lies conspire to keep Jim from learning the true story until the very end.
Number 9 in the Jim Nash Short Story Series.