An ambitious lab assistant carries out a forbidden experiment and accidentally creates a deadly bacteria which kills her and rapidly engulfs the city. The authorities order a curtain of secrecy and impose quarantine on all known contacts whilst embarking on a desperate search for a cure. Meanwhile one of the people in quarantine escapes and becomes the unwitting carrier of the disease. She spreads the plague wherever she goes and becomes a fugitive on the run eluding the police through subways and alleyways. In a gripping build up of events, the full horror of the plague becomes public and the onslaught has to be stopped before all human life on Earth is destroyed.