Six school friends meet up for a drug-fuelled Fourth of July weekend on a remote island.
What they don't know is the drug they scored is not what it seems; it's actually a new bioactive compound peddled by a sadistic right-wing terrorist organisation.
Anyone consuming it is then exposed to a virus causing fits of psychotic rage, mind-bending chaos and cannibalistic murder.
Only one refused to partake and now she must fight to survive as everyone around her, including her fiancé, tries to savagely kill her.