In the idyllic suburban town of Ipswich, Oregon, during the sweltering summer of 1984, a group of teenage friends grapples with the transition out of childhood. Davey Armstrong, a 15-year-old conspiracy enthusiast, spends his days with Eats, Woody, and Curtis, biking around the neighborhood and indulging in their collective sense of adventure. The tranquility of their summer is shaken when Davey becomes convinced that his neighbor, Officer Wayne Mackey, is the Cape May Slayer, a serial killer responsible for the abduction of thirteen teenage boys in the region. Fueled by a mixture of youthful curiosity and a desire for excitement, Davey persuades his friends to join him in an investigation to prove his suspicions.

As they set out to gather evidence, the boys employ childish spying techniques, thinking it's all a game. They stake out Mackey's house, take detailed notes, and devise plans to expose him without comprehending the potential danger of their endeavors. The closer they get to discovering the truth, the more they find themselves entangled in a web of danger and deceit. Their pursuit of answers begins to dismantle the innocence of their summer, confronting them with a reality far more serious and sinister than they ever imagined.