Ajidick President Kanna Iwakuni plans a ski tour with her boyfriend, Takuma Akahoshi.

What started as a small trip unexpectedly expands into a large tour of fifteen people.

From the eighth day of their two-week itinerary, they are hit by a severe blizzard.

The fifteen people are stranded at the mountain lodge Snowdrop.

That night, a severed head is discovered in Kanna's cottage.

The torso is found in the owner's cottage, which is a locked room.

Time idly passes, and during that time, the number of victims rises to nine.

Ultimately, four detectives who had previously investigated the case relaunch their investigation, guided by a documentary written by a reportage writer who questioned the conclusion that the culprit, Judgment, had hanged himself after leaving a suicide note.

Based on the revealed hints, the detectives track down the culprit, and after a fierce discussion, they succeed in making an arrest.