DAGANA - The Second Spawn (Book 2) by Kody Boye
I learn this the hard way when I witness a mermaid kill a surfboarder just off the coast of Mermaid Cove. With my small town in panic, and my future threatened as a result, I task myself with solving the town's mermaid problem.
The only problem? Events beyond my control leave all seeming lost—at least until I receive a mysterious letter from someone who claims to know not only about the mermaids, but a way to potentially rid us of their presence.
As the body count continues to rise, it becomes apparent that this one is smarter, faster, and far more dangerous than her predecessor.
And worst yet: she’s out for blood.