There is a day that changed the life of ex-commissioner Alexander Haller forever: On October 17th, 2017, he lost his fiancée Kara and his eyesight in a bomb attack. When a mysterious note appears on a murder victim with exactly this date, his successor, Laura Janda, asks him for support. However, there are tensions between the commissioner and her former mentor, because Haller believes in a conspiracy that he finally wants to uncover. They come across a lead in the police files: There was another death on the day of the attack on Haller. A man named Brandner, a suspect in a sexual offense, committed suicide while in custody. Was Brandner really guilty, as Haller still firmly believes? And what does that have to do with the current murder? Together with his right hand Niko, the former chief investigator rolls up the closed case again. While Haller is looking for the murderer, he is closer to him than he thinks. Because the stranger also has an open account with the investigator.