The film opens with a scene of an unknown assailant breaking into the home of two sisters. After one goes to sleep, the attacker subdues one of them using halothane and murders her after torturing her. After police questioning, the attacker, Jon Forster (Neal McDonough), is convicted by a jury after Gramm testifies against him in court. As Gramm leaves, Forster taunts him, saying "tick tock."
Nine years later, several similar torture murders with very similar modi operandi occur. Gramm is questioned but released. On the way to his class, he receives a threatening phone call telling him that he has 88 minutes to live until 11:45 a.m.. He reports the threat to Shelly (Amy Brenneman), his secretary, and brushes off the threat. He receives another call while teaching in his classroom, and he becomes suspicious of several of the students. A dean, Carol (Deborah Kara Unger), enters the classroom and warns everyone of a bomb threat, telling everyone to leave. Gramm finds a written threat on the overhead projector screen in the classroom. Gramm goes to the parking lot to see that his car has been vandalized with a similar threat with fewer minutes showing.
As Gramm walks toward campus security, he finds one of his students, Lauren Douglas (Leelee Sobieski), has been attacked by an unknown person in the same parking garage. Gramm reports this to the campus police after questioning nearby people at the garage exit.
Gramm later discovers, through a tape about his younger sister being killed years earlier, that someone had accessed his secure files. With the help of his teaching assistant Kim (Alicia Witt), Gramm tries to notify authorities while trying to uncover Forster's past at the same time. One suspect is Kim's former husband, Guy has been watching Dr. Gramm. Guy had spent time in the same prison as Forster.
His secretary, Shelly, who is a lesbian, finally admits that she was distracted by a woman who some how got a copy of the tape out of the secure area. As Shelly and the woman are lying on the couch in the office after their love making, the camera pans down and you can see it is Lauren there with her. The pieces begin to fit together.
Guy comes to Dr. Gramm's apartment about the same time as someone starts a fire in the elevator. As Kim opens the door to the apartment, some one on the lower landing, wearing a motorcycle helmet, opens fire and Guy is killed in a hail of bullets.
Parks wants to arrest Gramm now because of all the evidence piling up against him, but Gramm convinces Parks to give me just ten more minutes to find out who's behind all the murders and why. However Gramm has found out that a visitor to Forster on several occasions and identified herself as a "Lydia", one of his attorneys. He looked at a fax copy of her ID and sees the picture is Lauren.
Carol calls and tells Gramm to meet her in his office on campus at 11:40, she ends the call by giving Gramm a similar threat by saying "tick tock." Soon after, Kim calls Gramm telling him he has five minutes to meet her in another building on campus and she adds, "tick tock." Before leaving, he manages to convince Agent Parks (William Forsythe) to make a rendezvous with him at 11:40 in the other building on the 7th floor. Gramm arrives and finds that Lydia (who is actually Lauren under a pseudonym) had set this up and was working with Forster all this time.
Carol has been hung over a balcony by a rope around her heel, while Kim has been tied up in a chair. Lauren threatens Gramm with a gun and threatens to drop Carol if he doesn't drop his gun. She forces him to "confess" that he gave false details at the trial, but Parks has arrived is across the courtyard on the same floor. Gramm tells Lauren, but she doesn't believe him. Parks shoots Lauren just as the 88 minutes ends.
Both Carol and Lauren begin to fall from the 7th floor balcony. Gramm tries to save both but is unable to hold onto Lauren and haul up Carol, and so he chooses Carol over Lauren who falls to her death. He manages to pull Carol back up with the help of Parks. Just then, Lauren's cell phone rings and it's Forster calling, Forster laughs at Gramm and tells him to put his lawyer on the phone. He says when he gets out, he's going to come pee on Gramm's grave. Gramm tells him that Lauren is dead and that Forster only has 12 hours to live. Gramm then throws the cell phone over the railing and it smashes on the floor below.