In this episode, Heiji Hattori, Kazuha Toyama, Ooka Momiji and her butler Muga Iori are on the Shinkansen to Tokyo. A seemingly drunk man spills beer on Iori, who then cleans the stain in the toilet. There he finds a forgotten smartphone and answers a call.

The caller reveals that he knows Iori's identity as a former public security officer, and blackmails him. Momiji has been taken hostage, and Iori is to find a USB hard drive in exchange for her release. The caller instructs Iori to wake up a seemingly sleeping man in car 14, who, however, has already been stabbed to death.

Iori is to deposit the USB hard drive, which is said to contain incriminating material about the "Tsurugi scandal", at the location where the phone was found. While searching for the hard drive in the victim's luggage, Iori is interrupted by Heiji, but can fob him off with an excuse.

In a flashback, Iori's first meeting with Momiji three years ago is shown. At that time, Iori was a public security officer responsible for protecting Momiji's grandfather, a former prime minister. During an attack on the family villa, Momiji saved the injured Iori's life by bandaging him. This experience formed their close bond.

The caller continues to threaten to kill Momiji if Iori does not find the USB hard drive. The episode ends with a cliffhanger, leaving the resolution of the case and Momiji's rescue open.