A psychotic serial killer is unleashing indiscriminate death among the elderly, using a unique and diabolically dangerous device. The old folks are apparently dying of influenza and the deaths are accepted as from natural causes. DCI Tony Dyce is fighting a losing battle against a powerful, informed enemy. Shockingly, as the death toll increases and the investigation proceeds, Dyce learns that the killer is a highly disturbed figure from his own past. Constant, electrifying action leads to a terrifying climax, where the Chief Inspector’s own life hangs by a mere thread.