On the night of her final broadcast, the host of a popular late night radio show receives a call from an anonymous madman who has taken her entire family hostage, and who insists that she follow a strict set of instructions in order to save them from certain death. For the past seven years, Sun-young been kept insomniacs company with a radio show featuring film scores and soundtracks. But when her ailing daughter is forced to travel overseas for a life-saving operation, Sun-young plans a farewell broadcast as a means of saying thanks to her supportive fan-base. As the show gets under way, however, a man named Dong-soo calls Sun-young and claims he's holding her entire family hostage. Her only hope for saving them is to obey his commands on the air, and not offer any clues of the terror that's unfolding behind-the-scenes. With just two hours until the show is over, Sun-young races frantically to fulfill the malevolent caller's requests, knowing that with every mistake she makes, one of her loved ones will perish.