One night's park. The orange light floating in the dark sways up, down, left and right, rises, and then suddenly disappears.
The next morning, the stabbed body of Masahiko Isomura (Yu Miyazawa) was found in the park. Yu Amagi (Noriyuki Higashiyama), Yoshiki Ebisawa (Seiichi Tanabe), Michitoshi Sakashita (Nozomu Kotaki), and Shin Aoyama (Takashi Tsukamoto) who visited the site have no evidence of fighting in a place without street lights. , Also consider the crimes of acquaintances. However, the area around the park at night is dominated by darkness, and it seems difficult to find witnesses. Meanwhile, Ebisawa feels a fuss and relentlessly searches for witnesses with his reluctant Satoshi Komiyaji. On the other hand, Amagi and Aoyama started the investigation from a shoe mark different from that of the victim left on the scene.

Shigeharu Tomoda (Ryosei Tayama), a resident of the nursing home Dokudami-en, discovers the stabbed body of gym instructor Shoya Umeda (Jun Kanda) in a forest park early in the morning. In addition, badges distributed to staff at Dokudamien can be found about 30 meters away from the scene. Since the first discoverer was a resident of the same facility, the Investigation Division 1 asked the new full-time investigation team for support. Arata Aoyama (Takashi Tsukamoto) and Michitoshi Sakashita (Nozomi Kotaki) will work at a nursing home as an undercover investigator. On the other hand, Yu Amagi (Kiyuki Higashiyama), Yoshiki Ebisawa (Seiichi Tanabe), and Takumi Nonomura (Jin Shirasu) also pursue this case on their own.
Then, Aoyama and Michitoshi contacted the first discoverer, Tomoda. However, dementia has progressed due to the shock of the discovery of the body, and it is hard to hear, so it is useless. In addition, former detectives Isao Fujimiya (Tokuma Nishioka) and Shizuko Noma (Chieko Matsubara), who have both quirks and quirks, witnessed multiple suspicious people and a car believed to belong to the criminal on the day of the incident. say you did-
At that time, Aoyama is approached by Masaru Akatsuka (Kengo Yoshida), who is in charge of security at Dokudamien. Akatsuka was the person who caused a certain injury when Aoyama was in the juvenile division, but he has already rehabilitated and Aoyama asserts that he is a trustworthy person. However, Michitoshi is not convinced and has doubts about Aoyama's attitude as a detective.
　Following the investigation, it was discovered that the surveillance camera data on the day of the incident had been deleted. Michitoshi suspects Akatsuka, who is in charge of security, but when Aoyama protects him, Michitoshi's emotions explode.
Before long, Akatsuka was asked by the Investigation Division 1 to voluntarily accompany him, as the badge found near the crime scene matched his DNA, and there was also an eyewitness testimony that he was arguing with the victim. Michitoshi is relieved that the undercover investigation has been terminated, but Aoyama is worried about the unusual 'discomfort' drifting in Dokudamien...
Encouraged by Amagi's words, 'You can do whatever you want, Aoyama-kun,' Aoyama and Michitoshi continue their investigation of Dokudamien, but an unexpected fact is discovered...? What is the truth that Amagi and the others have arrived at while the intentions of the humans who are at the nursing home are intricately intertwined...?