When the body of an 11-year-old boy is found in the Georgia woods, Detective Ralph Anderson launches an investigation into the gruesome murder. With eyewitnesses and evidence pointing to local teacher and baseball coach Terry Maitland, Ralph makes a very public arrest.

During a surreptitious late-night visit with Terry, Ralph admits to being baffled by conflicting physical evidence. The next day, an unexpected tragedy throws the investigation into a tailspin, and Jack Hoskins is forced to cut his hunting trip short to return to work.

Despite being on mandatory leave, Ralph continues to scrutinise the confounding circumstances surrounding the night of the murder. Jack has a hair-raising experience at a remote barn where key evidence and a mysterious substance have been found.

While retracing the Maitlands' recent family vacation in Dayton, Ohio, Holly pursues a possible connection to an eerily similar case and gains valuable insight from local former detective Andy Katcavage. Meanwhile, Glory faces increased scrutiny in her daily life.

After returning from an eye-opening trip to New York, Holly searches for clues at several locations connected to the Dayton case. Jeannie finds herself shaken by an unnerving incident at work and delivers an ominous warning to Ralph.

Holly presents her unusual theory about the connection between two other mysterious child murders and the Frankie Peterson case. While Ralph remains sceptical, a more receptive Yunis suggests they start looking into Claude, the last person to have contact with Terry.

Holly makes a calculated attempt to help a volatile but conflicted Jack, while their whereabouts are tracked by Ralph and Alec. Confronted by town gossip on her first day back at work, Glory considers Howie's suggestion on how to secure her family's financial future.

Claude reconnects with his brother Seale in Tennessee, while Holly, Ralph, Yunis and Andy follow him in hopes of isolating the evil force and thwarting its next kill. Meanwhile, a family visiting a local cave festival narrowly avoids a dangerous encounter.

After obscuring their true purpose in town from local police, Ralph and Yunis interview witnesses from the cave festival, while Holly and Andy visit the scene. Later, the group considers its next move as Claude deals with the weight of his role.

The group finds itself in a climactic showdown in their last-ditch, desperate attempt to root out El Coco.