Anna Vlasova, daughter of a successful businessman, dies after a fall from the roof of a shopping mall. Investigator Borisov cannot find any motive for murder but does find traces of drugs in her blood. Kira, Anna's sister, refuses to believe that her sister's death was a suicide and decides to find out the truth behind the mysterious circumstances surrounding her sister's death. Kira persuades Borisov to keep the case open, and while he re-examines the evidence, Kira starts looking for clues to unravel the mystery. Events unfold at a frightening pace, and soon, one by one, all the people who were due to give evidence in Anna's case die mysteriously. Kira soon begins to realize that she may have to pay for the truth with her own life.