This book was referenced in the book Lone Star Sleuths - An Anthology of Texas Crime Fiction. Typically I would start with the first book in the series but I started with this one instead. It is by Carolyn Hart and is called Death On The River Walk. Henrie O is the short name for our sleuth Henrietta O'Dwyer Collins. She has come to San Antonio in search of her best friends' granddaughter named Iris. Iris typically contacts her grandmother on a regular basis but has failed to do so several times in a row. Henrie O is a retired reporter. When she discovers Iris has not been to her apartment and it has been searched through, her instincts tell her there is something not right.
She checks out Iris' place of employment and learns that Iris left there abruptly as well. In spite of the explanation given by one of the employees (and Iris' male friend), that Iris went to Padre with some other guy, she does not buy it and files a missing person report. She also speaks to several members of the family who operate the shop where Iris works.
She eventually gets a note to meet somebody on the River Walk and it turns out to be Iris. At this meeting another person shows up to grab Iris but she gets away. It turns out this person wants something Iris and Rick have taken from the shop and he wants it back. Later this person turns up dead at the shop and the package Iris had gets taken away from her in the mayhem created by a fire alarm. While Iris and Rick insists the package contained drugs, Henrie does not believe this to be the truth. She remembers recent news about a robbery at a museum in Mexico and suspects this is related. She is determined to find the reason behind this and to learn the identity of the killer in order to free another person of the suspicion.
Another person is murdered at the shop but it appears simply as an accident - Henrie O knows better. She knows somebody at the shop is hiding something. She sets out to investigate the family members and a select group of special customers who might be interested in the stolen treasures from the museum.
She discovers the stolen treasures in one of the customers' room where she is caught. She talks her way out of the room and discovers the identity of the person at the shop responsible for the theft. However her main concern is getting the person responsible for the murder captured in order to get the wrongly accused brother out of trouble.
She sets in motion a plan to capture the other person. But the person she suspected of the murder is not who she expected.
Later her friend's granddaughter and Rick get married and head off on there honeymoon in Mexico. While they are there, the missing treasures mysteriously show back up in the museum.