L is for Lawless is an atypical Kinsey Millhone novel. Millhone isn't technically hired to investigate; she just goes through the garage apartment of a deceased Second World War veteran to see if there's anything of interest to his heirs, and there isn't. Well, there's an old key marked "Lawless," but that's of only slightly more interest than nothing, at least until people start getting beaten up and killed over it.
The ensuing shenanigans take Millhone on a picaresque journey from Santa Teresa to Dallas to Louisville. Sue Grafton somehow pictures Dallas as being in the desert (I suppose there's no conquering this preconception except by bringing people to Dallas one by one and refuting it visually). She even has Millhone and some absconding fugitives take refuge in a hotel called the Desert Castle: seriously, there are no establishments in Dallas called "Desert" anything, because you'd instinctively stay away from them; names like that are reserved for cities actually in deserts, like Las Vegas, or ironically for Southwestern restaurants in places like Duluth.