When two hikers go missing outside of Denver, Colorado, FDLE special agent Amy Larson and her partner, FBI special agent Hunter Forrest, have good reason to suspect foul play. The pair of hikers are only the latest to vanish after a rash of disappearances that's left local law enforcement stumped. But in searching near the Arkansas River, the agents aren't prepared for the horror they uncover: a muddy pit littered with corpses. When a tiny toy horse is found on the scene, Amy and Hunter recognize the calling card. They'll have to move quickly before the body count can grow. Their investigation soon draws them down the rabbit hole of a dangerous cult with a sinister mandate, one that involves human sacrifices. But when more people go missing, it becomes clear the cult's reach extends beyond state lines, leading Amy and Hunter deep into the Florida Everglades to set a perilous trap, one that stands to risk everything they hold dear, including their lives.