Mitch McDeere is a graduate of Western Kentucky University with a degree in accounting, who passed his Certified Public Accountant exam on the first attempt and graduated third in his class at Harvard Law School. Mitch is married to his high-school sweetheart, Abby McDeere. His older brother Ray is imprisoned for manslaughter, and his other brother, Rusty, died in Vietnam. His mother has mental health issues and lives in Florida.
Mitch receives an unusual offer from Bendini, Lambert and Locke, a small tax law firm based in Memphis. The offer includes a large salary, a new car, and a low-interest mortgage on a house. Soon after he joins as an associate, he passes his bar exam.
Two of Mitch's colleagues, Marty Kozinski and Joe Hodge, die in a scuba diving accident in the Cayman Islands a few days before he starts at the firm. During a memorial service at the firm, Mitch notices plaques commemorating three other attorneys who died while working at the firm, one in a car accident, one in a hunting accident, and one by suicide. Suspicious, he hires a private investigator, Eddie Lomax, an ex-cellmate of Ray, to investigate the deaths.
Lomax discovers that the three attorneys died under suspicious circumstances. He cautions Mitch to be careful and is later murdered. FBI agent Wayne Tarrance confronts Mitch, telling him the FBI is watching the firm.
While Mitch is in Washington, D.C. on business, Tarrance approaches him again, this time alongside FBI Director F. Denton Voyles. They reveal the firm is a front for the Morolto crime family of Chicago. The firm's founder, Anthony Bendini, was the son-in-law of Morolto. For almost 50 years, the firm has lured young lawyers from humble backgrounds. Although Mitch's work has been legitimate, the partners and senior associates are deeply immersed in a tax fraud and money laundering operation that accounts for up to 75% of the firm's business. Any firm member that tries to leave is killed before they can talk. Kozinski and Hodge were in contact with the FBI at the time of their murders, leading Voyles to take personal charge of the investigation.
Mitch learns his house, office, and car are bugged. The FBI tells Mitch that in order to get enough evidence to bring down the firm, he must reveal information about his clients, including his legitimate clients, potentially ending his legal career. The FBI warns Mitch that he will almost certainly go to prison if he chooses to ignore them. The firm also investigates Mitch; the firm's security chief, DeVasher, suspects he is talking to the FBI.
Ultimately, Mitch and Abby decide to cooperate. Mitch promises to collect enough evidence to bring down the firm in return for $2 million and Ray's release. However, they secretly decide to flee after turning over enough evidence to topple the firm, since they do not trust the FBI.