Near the end of camping season, a group of senior counselors and campers—including T. P., [Tony Fish], Betsy, [Gaylen Ross], Ellie, [Jan Claire], Dave, [Seth Jones], Stacy, [Harriet Bass], Bill, [Alexander Murphy Jr.], Richie, [Jimmy Steele], and the seasoned head counselor Max—gathers around a crackling campfire to swap stories and share a sense of fatigue from the long, outdoor week. The storyteller in the group, Max, unfolds the legend of Madman Marz, [Paul Ehlers], a killer who murdered his wife and children with an axe in a nearby abandoned house. He was lynched and scarred by furious villagers, yet somehow escaped into the woods, a figure said to gnaw at the edges of the camp’s peace. Max warns that merely saying his name aloud can summon him, a reminder that the story isn’t just a bedtime tale but a threat lurking beyond the trees.
Despite the caution, Richie tests the myth, shouting Marz’s name and hammering a rock through the window of the old home as a pointed message to Max. The act unsettles the camp, and the group returns to their tents, though the danger feels closer than ever. The night takes a darker turn when Marz arrives in earnest, and a series of brutal, grisly events begins to unfold.
Max steps away to fetch supplies, leaving the others under less watchful eyes. The camp’s drunken chef is killed by Marz, a stark sign that the legend has become a terrifying reality. When Dave discovers Richie’s disappearance, T. P. heads into the woods to search, only to be caught by Marz and hanged from a tree with a rope. Dave soon follows in a brutal twist, decapitated by Marz as the search intensifies.
Stacy grows suspicious and urges Ellie and Bill to stay cautious while she drives out to find the truth. She locates Dave’s body in a shocked moment and tries to escape in her truck, but Marz leaps onto the hood, severing her head as she is pinned under the vehicle. Ellie, realizing something is terribly wrong, returns to the campsite with Bill, and the two attempt to flee in a vehicle, but Marz forces Bill from the truck and kills him. Ellie staggers back to the cabins, where she is ultimately struck by Marz and collapses in the chaos.
Meanwhile, Richie wanders back to Marz’s house, drawn by the night’s events and the fear that refuses to quiet. Betsy, watching through the cabin window and hearing the alarm, phones Max to warn him and arms herself with a double-barrel shotgun after glimpsing Marz moving through the camp. In a tragic turn, she accidentally shoots Ellie when Marz throws her against the cabin window, startling the sleeping children and sending everyone scrambling for safety.
With the camp in turmoil, Betsy moves to confront Marz in his house. She faces the killer, but he overpowers her, dragging her down to the basement where he has stored the bodies of his victims, including those of his wife and children. In a final, brutal moment, Marz impales Betsy on a coat rack, but she manages one last wound with a hunting knife before dying, causing a candle to topple and ignite the room. The fire consumes the house as Marz escapes into the forest, leaving the scene of devastation behind.
As Max drives back toward the campsite, he encounters a shaken Richie on the road, who tells him that Madman Marz is real and not just a campfire story. The final image lingers on the forest, where Marz is seen again, lurking among the trees and waiting for the moment someone daring enough to speak his name might summon him once more.
