University students Yuzuru Hamura and Kyosuke Akechi, who are both interested in Mystery Novels; with student Detective Hiruko Kenzaki from the same university, attend a summer camp and stay at Shijinso pension in the mountains. On their first day there, they must barricade themselves in the pension. The next morning, they discover a murder has taken place in the pension. ~~ Adapted from the novel "Shijinsou no Satsujin" by Masahiro Imamura.