A crowd has gathered for a popular band’s live performance. However, a woman stabbed to death and a man called Ishigari is overpowered by eyewitnesses. The next day, while Usui Koichi is accompanying his daughter Haruna, who lives separately with his estranged wife Yoshiko, to a piano competition, he happens to encounter the stabbing of a woman at a train station. A male suspect called Noma who had been subdued by commuters is quickly arrested. Then e is ordered by Nishikawa Shusaku to participate in the investigation into the series of fatal stabbings because he was a witness in this case. ~~ Adapted from the novel series "Keibuho Usui Koichi" by Konno Satoshi.