Caught in a storm at sea, fallen overboard, the protagonist awakens to find themselves washed ashore on a deserted island. Seeking help, they wander the vicinity until they discover a Western-style mansion. Their relief at being saved quickly turns to horror as they find multiple corpses strewn inside the mansion.

The protagonist is aghast at this unexpected turn of events. To understand what has happened, they check the contents of a video camera found near one of the bodies. It reveals footage of ten people who had gathered on the island, and the horrifying tragedy that befell them. They were shot dead by a killer wearing a wolf mask. Furthermore, the killer appears to be one of the ten people gathered on the island. However, the victims themselves didn't suspect one of their own; they were convinced it was the work of an outsider.

Upon learning this fact, the protagonist falls into despair. If they try to seek help by finding and contacting survivors, they'll be mistaken for the killer. Worse, they might be judged guilty and killed. Moreover, if a survivor they seek help from turns out to be the killer, they'll be seen as a nuisance and murdered.

In order to identify the killer among the ten nameless individuals, and in a situation where they could be attacked by either a survivor or the killer at any moment, the protagonist begins exploring the mansion, searching for clues that will lead to the killer...

This work passed the preliminary selection for the 62nd Edogawa Ranpo Award.