Spilled Blood by Brian Freeman

A taut thriller about two rural Minnesota towns locked in a deadly feud-and a teenage girl caught in the crossfire
Linked by the Spirit River, the two towns couldn't be more different: in affluent Barron, a powerful and secretive scientific research corporation enriches its residents, while downriver in blue-collar St. Croix, victims of that company's carcinogenic waste struggle to survive. The bad blood between the communities escalates into open warfare when the beautiful Ashlynn, daughter of the corporation's president, is found shot dead-and a St. Croix girl, Olivia Hawk, is accused of the crime. Reluctantly, Olivia's mother summons her estranged husband Christopher, a Minneapolis lawyer, to come defend his daughter. As Christopher struggles to unravel the mystery of Ashlynn's murder and save his own daughter, he uncovers some ugly truths that endanger the residents of both towns. And looming over everything are the chilling, apocalyptic threats from a murderous psychopath known only as "Aquarius."