Shelly's mother was a mermaid, her dad human. After their deaths, she goes to live with her cousins, Jet and Lily. Jet and Lily are full blooded mermaids. Mating with a human is a no-no and Shelly has some baggage from her parents relationship. Tillman moved back home and took over his dad's position as sheriff when he died. His mother is an alcoholic and his younger brother is severely developmentally disabled.
Shelly, while out for a swim, unwittingly meets a serial killer. This added some suspense to the plot. There are some things she should have done, but oh well. Tillman's brother, Eddie, adds to the plot and makes him realize when he's being an unfair asshole.
I love mermaids and there's not many books featuring them. Some more backstory would have been nice. Jet and Lily's stories are coming in books 2 and 3, so maybe I'll get some more. What is here was interesting. I loved all the treasure they have from shipwrecks. And being able to hear/communicate underwater. And they eat a lot of seafood.
Some continuity issues- One moment Eddie is with Tillman and then later he's not (it mentions he finally feels asleep. Nothing said about taking him home. I remember this one because of what Tillman does.)
I say this meets for the non-mammal shifter because of this: "Mermen and mermaids gathered in a remote South Pacific island for a week of orgies. Those inclined to produce a litter of merchildren built undersea nests in beds of coral for fertilizing and hatching their newborn." I was hoping for some elaboration, but this was it. Different and interesting.