Lapped by the gentle waters of Locust Lake, the resort town of Tranquility, Maine, seems like the perfect spot for Dr. Claire Elliott to shelter her adolescent son, Noah, from the distractions of the big city and the lingering memory of his father's death. But with the first snap of winter comes shocking news that puts her practice on the line: a teenage boy under her care has committed and appalling act of violence. And as Claire and all of Tranquility soon discover, it is just the start of a chain of lethal outbursts amount the town's teenagers.

As the rash of disturbing behavior grows, Claire uncovers a horrifying secret: this is not the first time it has happened. Twice a century, the children of Tranquility lash out with deadly violence. Claire suspects there is a biological cause for the epidemic, and she fears that placid Locust Lake may conceal an insidious danger. As she races to save Tranquility -and her son-from harm, Claire discovers an even greater threat: a shocking conspiracy to manipulate nature and turn innocents to slaughter.