She didn't know how fast the current was moving her. It could take many more hours yet, perhaps more hours than she had the strength for. But she must not stop. She must keep going. She must try to catch the river boy, even though she was frightened at the thought of what he was.

Jess's beloved grandfather has just had a serious heart attack, but he insists that the family travel as planned to his boyhood home on the river so that he can finish his painting, River Boy. As Jess helps her ailing grandpa with his work, she becomes entranced by the scene he is painting. Then she becomes aware of a strange presence in the river -- a boy who asks for her help and issues a challenge that will stretch her swimming talents to their very limit. Jess knows that Grandpa and the river boy are connected, but how? Can she take up the river boy's challenge before it's too late for Grandpa?