Jack Gramm (Al Pacino) is a forensic psychologist for the FBI, as well as a university teacher. When the movie begins, a convicted killer named John Forster (Neal McDonough) is on death row awaiting his execution, thanks mostly to Gramm's testimony during the trial. Forster has become a celebrity as he does interviews and is appealing his execution date. A rash of copycat killings spring up (mostly of women Jack knows) making the police doubt Forster's guilt and suspect Gramm of being the culprit.
At the same time, Jack gets a mysterious phone call telling him he'll be dead in 88 minutes. He then races to find the mystery caller, along with one of his students, Kim (Alicia Witt). The remainder of the movie after he gets the call is exactly 88 minutes.
In the end, the person responsible for the murders is another one of Jack's students, Lauren (Leelee Sobieski), who had previously been a part of the legal team handling Forster's case. After getting seduced by him and vowing to help him, she killed the women, to throw doubt on Forster's guilt, thus enabling him to appeal his execution and possibly go free. She also made Jack a suspect in the killings and cast doubt on the testimony he had given during the trial.
She also plays on Jack's past by sending him a recording of the time when his sister got killed, a recording which he kept under tight security in his office. Lauren was able to get it by seducing Jack's lesbian secretary, played by Amy Brenneman, during a party, which gained her access to Jack's personal files.
In order to further throw him off, Lauren holds both Kim and another teacher (Deborah Kara Unger) hostage, forcing them to call Jack and announce themselves as the mystery caller. Jack arrives at the scene, with Deborah hanging from the rafters of a sixth floor and Kim tied to a chair. After an argument in which she reveals the whole scheme, Lauren gets shot by Jack's cop friend (William Forsythe) who had earlier been alerted to what was going on. Lauren falls to her death and the other two women are saved.
Forster calls Lauren's cell phone inmediately after and gets Jack. He reveals the entire plan in more detail and is confident he'll be pardoned, until Jack tells him his associate's dead and the cops know the truth. Forster is convicted of the crimes and executed by lethal injection.