A squad of nine Louisiana National Guardsmen embarks on a weekend exercise in the Louisiana bayou, a vast swamp they are ill-prepared to navigate. Leading the pack is Cpl. Hardin, a recent transfer from Texas who is skeptical about the leadership and experience of his new unit. As they journey further into the swamp, tensions mount among the men, mostly non-military part-timers who lack discipline and are ill-equipped with live ammunition and scant survival provisions. Their mission is to reach a specific point in the bayou by navigating with old maps and compasses, simulating a standard war exercise.

The exercise takes a dangerous turn when the squad steals three canoes from the local Cajun inhabitants without asking for permission, crossing a clear boundary of respect. When they encounter the Cajun hunters, a grave misunderstanding ensues as one of the guardsmen foolishly fires blanks to scare them. This incites a real and deadly response from the Cajuns, who know the treacherous swamp far better than the intruders. The guardsmen find themselves in a real battle for survival, facing unfamiliar terrain and an invisible enemy that seems to anticipate their every move. As they wade deeper into the Cajun territory, their journey transforms into an inexorable descent into paranoia and fear, stripping them of the bravado with which they started.