A Mother's Vow — K.N. Casper

There is corruption in the Houston Police Department

And because she is chief of police, that makes it Catherine Tanner's problem. So when evidence turns up to indicate that her husband might not have died of natural causes, she has to go outside her own precinct to investigate.

Ex-cop Jeff Rowan is the most logical person for her to turn to. Unfortunately, Jeff isn't inclined to help Catherine, considering she was the one who fired him.