After a home invasion leaves his wife and daughter dead, Clyde Shelton (Butler), a retired "Think Tank", is told that one of the criminals who killed his wife and daughter will not be convicted, as much of the evidence against him was compromised by a bungled forensic investigation. After Shelton pleads with Nick Rice (Foxx), a power-hungry attorney with a 96% conviction rate, to take the case to court, Rice tells Shelton it does not matter what is right, but what can be proved in court. Rice then makes a deal with Clarence Darby, the person who raped and murdered Shelton's wife and daughter, for third-degree murder, while his accomplice, Rupert Ames, is sent to death row, for a charge of what is essentially theft.


Ten years later, Ames is executed; due to a chemical alteration, he dies an agonizing death. Initial evidence leads to Darby, who fires repeatedly at police after being contacted by a stranger. After being led to a cop car, Darby is directed to an abandoned warehouse, where the police officer, Shelton in disguise, poisons and tortures Darby to death. Rice quickly arrests Shelton, who is found naked in his home, surrounded by law and engineering books.


Rice arrives to interrogate Shelton, and congratulates him on removing Darby from society. Shelton initially confesses to the crime, and Rice begins to depart, when Shelton points out that his statement is not a confession by any stripe, at least, not that can be proved in court. During this, Rice's family, whom he maintains strained relations with, receives a DVD of Shelton torturing Darby to death. Shelton agrees to make a real confession in exchange for an expensive mattress in his prison cell. Despite his disgust, Rice agrees after being ordered, as there is virtually no real evidence connecting Shelton to the murder. The following day, Shelton makes a case, using multiple obscure legal precedents, to have his confession thrown out. After the judge, the same who presided in Darby's trial, agrees, Shelton begins a tirade, railing against the judges myopia for the law vs justice, and is removed for contempt.


Rice meets with Shelton again to get a new confession, and Shelton wants to make another deal, for the life of Bill Reynolds, Darby's attorney. Shelton claims that Reynolds is alive, and will give his location in exchange for an expensive steak dinner delivered at precisely 1 p.m., along with music from his iPod. Despite his demand, Warden Inger forces multiple searches, resulting in Shelton receiving his lunch at 1:08. Giving his location, Rice goes on a 15 minute helicopter ride to find Reynolds buried alive and only minutes dead, with Warden Ingers delay causing Reynolds to suffocate. Shelton, after finishing lunch and sharing with his cell mate, brutally murders him, and is thrown in solitary.