In March 1989, Sweden was rocked by the murder of ten-year-old Helen Nilsson in Hörby, a town in the south of the country. The child was raped and strangled. The case remained unsolved for sixteen years. This series follows the relentless journey of police officers Per-Åke Åkesson and Monica Olhed, who led the investigative team that eventually, against all odds, found Helen's killer.