When her older sister’s son is kidnapped, Kotomi, who is determined to help her and her brother-in-law, goes against the kidnapper’s demand and notifies the police. The detective (Keisuke) in charge of the case surrounds the ransom drop-off location to make the arrest, but the kidnapper never shows up and the son is never seen again…Two years later, Kotomi gets married to a man named Makoto. Her sister and her husband pay Kotomi a visit to throw a party and celebrate this wonderful occasion. That night, the two sisters, who had grown apart since the kidnap incident, slept alone together.Kotomi is awakened by an alarm clock, only to find out that she is not in her room, but in a ruined deserted factory with only her underwear on and limbs tied. Next to her lies her sister tied up in the same fashion. In front of the two sisters calling for help appears a man wearing an ominous mask. The man’s deranged game begins as he repetitively violates the sisters.