Horns and Wrinkles Reprint edition

How can you tell if a rivers under a spell? River trolls, rock trolls, blue-wing fairiesthe usual suspects. The stretch of the Mississippi where Claire lives has rumors of them all, not that shes ever spotted any. But then Claires cousin Duke takes a swim and sprouts a horna long, pointy, handsome thing. After that, Claire doesnt have much choice but to believe that something rivery is going on, especially since shes the only one who can help Duke lose his new addition.