The mysterious disappearance of Helena Andersson remained one of the Swedish police's darkest mysteries for 30 years. All official investigative efforts to find answers ended in a stalemate, leaving the young woman's family in the dark. However, journalist Fredrik Undevik begins his own investigation, which sheds light on hidden details of the case. His findings force a re-examination of the events of that fateful night and point to new evidence. A team of experts attempts to reconstruct the chain of events where justice failed.