This time, Felix Fischer is investigating the sudden death of a young but already well-known opera singer, Anna Glinskaya. It turns out that Valeria is well acquainted with Glinskaya's husband, Professor Pichugin, and once even studied with him. Having learned that Pichugin is suspected of the murder, Valeria considers it her duty to help the professor protect his good name. The professor shows the girl a selfie his wife sent him the night of the murder. The mystery is that, judging by the investigation, by the time the photo was sent, Anna was already dead .