HE is the river. HE takes who he wants and releases who HE wants. 

Emmy Jenkins knows what it feels like to have a serial killer come after her. She escaped HIM twice. Emmy and Brian must start over in a new town, away from the tragic events and the killer's family. Unfortunately, HE escapes custody. The authorities think the killer committed suicide by drowning himself in the river. They do not locate his body, but they do find a girl drowned in Elk Lake. Her death is ruled an accidental drowning, but Emmy knows HE is still alive. And HE is coming for her. 

To prove himself worthy of immortality, HE follows the river to its source in the Cascade Mountains, where HE will accept whatever the headwaters offer. Suddenly, his destiny is revealed when the perfect nymph with three little girls appears on the shore.