In a sleepy country village, Detective Inspector Robin Marshal - now in retirement - is nearly killed by a stranger. His friend Alice, a police psychiatrist, discovers that the murder attempt was almost certainly ordered by a terrifying criminal, 'Big Mack', currently incarcerated in a notoriously violent prison. There his criminal kingdom controls not only the inmates, but many of the guards, through the power of money and the threat of extreme violence.
When Alice goes to work in the prison to find out more, she, too, becomes a target, her car machine-gunned on a country road; and Robin is attacked again while recovering in Spain.
Under pressure from an outraged public and with political concern rising, the authorities try to put a stop to Big Mack's activities. But everyone is under threat when he is suddenly at large following a murderous escape.
How can this evil man be stopped?