A broadcasting station employee discovers a lost cassette recording gathering dust in a storage area and brings it to a radio show hosted by an idol member. On the tape, there is a faint humming sound of a girl. Concerned about a missing group member, the idol's manager employs a private investigator to find him within three days, just in time for a big concert. The investigator interviews each individual in the hopes of solving the mystery. As the inquiry proceeds, however, the idol members succumb to a terrible curse, falling to terror one by one. As the detective examines the identity of the mystery voice on the recording, it becomes clear that the cursed cassette tape holds the answer to their problem.