Synopsis In December, the luxurious PeaceLand Cruise sets sail with 500 souls aboard. Among them is David , an officer of the National Investigation Company, seeking rest during his leave. But when AI Security detects a mysterious 501st passenger who appears at night and vanishes by morning, David is thrust into a chilling investigation. Together with Captain John , he must uncover whether this anomaly is a glitch, a criminal, or something beyond human comprehension. As the voyage continues, David discovers a strange phenomenon — the passenger can only be seen through water reflections. What he finally witnesses shakes the boundary between science and myth: a human-like figure with the face of a fish. The suspense builds as David races against time to understand the truth before the cruise ends. Though the voyage concludes safely, the mystery remains unsolved, leaving David — and the world — haunted by the possibility of creatures that exist beyond human perception.