Trapped inside an A-rank Monster Stage where previous teams have died, a group of investigators faces a deadly predicament: reinforcements cannot enter, and the one-way teleport trap seals their fate. Despite the strict rules forbidding noise and movement during the ominous 'performance,' tensions rise as they encounter the terrifying Opera Monster. The lead investigator steps forward to confront the threat with confidence, challenging the deadly taboo. As the hostile environment escalates and the final act nears, it becomes clear that all guests will die once it concludes, leaving the group racing against inevitable doom.