Daisy and Violet Schramm are twin sisters who had a difficult adolescence, in part because their mother rarely got out of bed after they turned 11 and in part because they were mocked by classmates for having "senses" (essentially ESP). The two reacted differently to these experiences--Violet became a professional psychic while Daisy changed her name to Kate and attempted to "destroy" her powers and disappear into a conventional life with her perfect husband Jeremy and their two toddlers.
As the book opens, a small earthquake has hit St. Louis, where both twins still live as adults. Violet soon thereafter predicts that a major earthquake will hit the city on October 16, and her prediction becomes the talk of the nation. Jeremy, who is a geoscientist, believes Violet is wrong but seems to tolerate his sister-in-law's foolishness, in part because he doesn't think Kate believes Violet's prediction. The first two-thirds or so of the book is about how Kate tries to "help" Violet (always as a way of controlling her) and their widowed father. This part of the book, despite the more boring twin getting most of the attention, is somewhat interesting--I enjoyed the exploration of the twins' relationship and the media response to a sensational story. But then the book suddenly shifts and becomes about something else entirely--I won't say what happens to change the focus so as not to be a "spoiler." Suffice it to say that the last third of the book is ridiculous and predictable and ruins any enjoyment one might have found in the book.