While heading home, Hatsuumi Wataru answers a frantic distress call, only to arrive at a crime scene discovering a dead body and his traumatized sister, Sara, trembling in a corner. Desperate to shield his sister from the accidental killing, Wataru asks a generative AI: “Based on the following conditions, tell me how to execute a perfect crime.” Following the AI’s step-by-step instructions to wipe out all traces, the siblings soon find themselves sucked into a much larger vortex of sin. When a mysterious woman suddenly appears, will the desperate siblings ever obtain the answer that sets them free?