In a small, tranquil Iowa town, a mysterious toxin inadvertently introduced into the water supply begins to take a frightening toll on the residents. The contaminant, a biological agent inadvertently released from a crashed military airplane, transforms the townspeople into violent, deranged beings. Sheriff David Dutton, alongside his pregnant wife and the town's doctor, Judy, notice bizarre behavior gripping their friends and neighbors, signaling the onset of chaos. When the town drunk staggers onto a local baseball field during a game, exhibiting strange symptoms and brandishing a shotgun, David is forced to take lethal action, an event that marks the outset of widespread panic and a descent into madness for the once-idyllic community. As the situation escalates, the couple, together with Judy's assistant, Becca, and Deputy Russell Clank, struggle to maintain order and sanity in the face of the growing threat.

As the military arrives to contain the outbreak, imposing a strict quarantine and separating the infected from the healthy, the town's social fabric disintegrates, and the lines blur between friend and foe. Attempts to evacuate the uninfected are met with severe obstacles as the military's agenda becomes questionable and communication breaks down. The small group of survivors must navigate a landscape of desperation and violence, where anyone they encounter could be a carrier of the deadly virus. The quintet's trust, loyalty, and resourcefulness are tested to the limit as they attempt to escape the town and seek refuge from the spreading madness that threatens to consume them all.