A Red Herring without Mustard is the third in the Flavia de Luce novels and I find the stories to be a treat. I want to swoop in and tell her bratty sisters to stop it and play nice. I would like to smack her detached Father and tell him to wake up! Yes, your wife has moved on to the next life but, really, get a grip and start paying attention to these three girls you have. In other words, I become an engaged reader and that is usually a good sign.
You don't have to read the books in order but I do think it helps since 11 year old Flavia looks back a few times at previous incidents. She snoops around on her trusty bicycle, Gladys, solving crimes in her little village of Bishop's Lacey and spends time in her laboratory at her ancestral home, Buckshaw, plotting ways to seek revenge on her two older sisters. Anyway, Alan Bradley has written a fine series that I recommend.