A psychotic serial killer is unleashing indiscriminate death among the elderly, using a unique and diabolically dangerous device. The old people are apparently dying of influenza and the deaths are accepted by the medics as from natural causes. Sheriff Cnut and his team are fighting a losing battle against a powerful, informed enemy. As the death toll rises, Cnut is shocked to the core to find that the killer is a highly disturbed figure from his own hidden past. Constant, electrifying action leads to a terrifying climax, where the Sheriff's own life hangs by a mere thread.