Twelve-year-old Eddie has always lived for fishing trips with his grandfather, idyllic day-long floats on the sweet waters of their home river. But now Gramps, the charismatic owner of a local sporting goods store, has himself been hooked by dementia: he's obsessed with catching the biggest fish in the river, and he's scaring everyone in Eddie's life half to death. This earthquake spawns numerous aftershocks, some comic: the unfortunate incident of the deceased carp; how it comes about that Eddie's dad throws up at his mom's wedding. And some dark: the climactic 60-mile river journey—one voyager perhaps mad, the other perhaps kidnapped—launches deep in the night, carrying Eddie and his grandfather inexorably to a final, fateful encounter with the Big One.