The Brethren by John Grisham

Trumble is a minimum-security federal prison, home to drug dealers, bank robbers and three former judges known as The Brethren.

Each day in the law library, The Brethren spend hours fine-tuning their mail scam, and it's starting to pay big.

But when their scam goes awry and ensnares the wrong victim - a powerful man on the outside - they're in trouble. Because this man has dangerous friends.

Just as the prison failed to protect society from The Brethren, it won't protect them from their victims...