The Brethren (English, Paperback, John Grisham)

Trumble is a minimum-security federal prison, home to the usual assortment of relatively harmless criminals - drug dealers, bank robbers, swindlers, embezzlers, tax evaders, and three former judges who call themselves The Brethren. They meet each day in the law library where they handle cases for other inmates, practise law without a licence, and sometimes dispense jailhouse justice. And they spend hours writing letters. They are finetuning a mail scam, and it's starting to really work. The money is pouring in. Then their little scam goes awry. It ensnares the wrong victim, a powerful man on the outside, a man with dangerous friends, and The Brethren's days of quietly marking time are over."