River Marked

I just love this series!! Mercy and Adam are camping on the Columbia River. When Mercy goes in the water to save a distraught fisherman, what she thinks is a weed wraps around her and when she finally gets rid of it, she sees that she has been marked. The fancy camper and campground loaned to them start to seem a little premeditated. Did someone point them in the direction of a monster in the river? Once again, Mercy has good intentions, but finds trouble instead.