Lieutenant Colonel of the Metropolitan Police Anna Sterkhova came on a business trip to investigate archival cases that at one time remained unsolved. And local resident Elena Vasilievna Kolodyazhnaya immediately contacted her - she asked to pay special attention to the case of the murder of her mother. It happened more than thirty years ago, right before the eyes of Kolodyazhnaya, who was only ten at the time. The perpetrator was never found, and the woman still could not recover from this monstrous murder; it continued to haunt her even years later. Anna decided to reopen the closed case and re-examine the material evidence, but it turned out that it had disappeared from the archive without a trace...