Jessica (Kim Basinger), a high school science teacher, was kidnapped. Fortunately, there was an old-fashioned dial-up phone where the criminals imprisoned her. In a panic, Jessica randomly dialed a number for help, and her call for help was made to the mobile phone of the young man Ryan (Chris Evans). Ryan thought it was a prank at first, but then the criminals found Jessica calling for help and smashed the phone. Hearing the roar of the criminals and Jessica's exclamation, Ryan realized the seriousness of the situation. After the criminals left, Jessica used her knowledge of science to reassemble the phone and reconnected with Ryan. Through her story, Ryan learned that the criminals would soon kill her husband and son, and Jessica didn't even know where she was. Ryan didn't have much time left, not to mention that his mobile phone had limited power. Ryan must do everything he can to save the lives of Jessica's family.