In Hawaii, FBI agent Karen Vail pursues a killer without a profile, in this thriller by the USA Today bestselling author of The Darkness of Evil. When Det. Adam Russell of the Honolulu PD encounters the body of a woman in her sixties—the second in recent days to inexplicably die of what seem like natural causes—he reaches out to Karen Vail, the renowned FBI profiler, who hops on the next plane. But even for someone as fluent in the language of murder as Vail, this case is hard to read. How were these women asphyxiated with no signs of trauma? How can she gather clues or collect evidence when the killer seems to strike during the briefest casual encounters? Is this the behavior of a male or a female perpetrator? And perhaps most terrifying of all, if the deaths appear so natural at first glance, how many victims have already been overlooked? Now, as something cold and dark lurks under the sunny warmth of this island paradise, Vail must stop a serial killer as elusive as the breeze … Contains mature themes.