Vendetta by Ed Gorman

Joan Grieves has only had her father home for a couple of months when he leaves again in the middle of the night to avenge the person responsible for putting him in jail on a trumped up charge of embezzlement. When she receives a telegram advising her to expect her father's body by train, she reaches out to Father Pete Madsen, a man troubled by his past. Madsen struggles with his conscience, wanting to help Joan, yet hating to pick up the gun that has caused his grief. Gorman writes a brilliant tale of friendship, love and hate. A good read.