When the book opens, Puller is contemplating returning to work after a brief vacation taken to recover from the events of Zero Day, when his father receives a worrying letter from Puller's Aunt Betsy, who lives in Paradise, Florida. She alludes to something dodgy going on and "mysterious happenings at night". Puller goes down to Florida to visit his aunt, but when he gets there he discovers that she has recently deceased, having drowned in her backyard in what the police have decided was an accident. Given the letter she just wrote, Puller is not convinced it was an accident and starts to investigate further. Almost immediately it becomes apparent that there is more than meets the eye to the entire affair.