Undercurrent is about Callum Harris, a teenager who after falling over Crystal Falls, wakes up in a hospital in a world completely different to his own. The beginning of the book was kind of slow, as it was spent completely in the hospital as Callum is recovering. But as the story progresses it becomes more fast paced.
Callum learns that in this world he is a star athlete, who is a complete troublemaker, similar to how his brother is in his original universe. In this universe we learn that his brother Cole was paralyzed in a waterpark accident. The sheriff here is suspicious of Callum as another teenager in town disappeared at the same time he went over the Falls, and was last seen with him.
As the book gets more to the end he comes to realize that this is an alternative universe, with the help of the alternative version of his best friend Willow.
The ending while not awful wasn't the best I think it could have been. Undercurrent overall was a really enjoyable book, and I really want to read more from Paul Blackwell.
I won an arc copy a while ago from goodreads first reads. I decided to reread then re review it since the last review I did was awful.