"A cult worships a mermaid that will usher in a new, underwater world. In the village of Hopwas, there is a barbed wire fence around the old reservoir - but it's not meant to keep something out, it's meant to keep some things in. Now a wealthy man is being driven mad by a terrifying vision. A drowned corpse is found in a dry, empty field. Suddenly, a child is gone. And something even more horrific is waiting to be released.
Almost finished this; not one of Guy's better ones but I'm enjoying it.