Near the town of Ennis, Montana, local doctor and former government research immunologist Wesley McClaren (Steven Seagal) who has an interest in herbal medicine and is also a weapons and self-defense expert, is called to a hospital when people start dying from an unknown but very deadly disease. He determines that the cause is a highly dangerous airborne virus and calls in a Biological Response team, who seal off the town while doctors start treating sufferers with a vaccine. Unfortunately for them, several have already died.