A late summer night in 1990 a young pregnant woman is brutally murdered by being buried in the sand, to slowly become submerged by the tide. 25 years later, the sadistic murder remains unsolved. Olivia Rönning receives the task of studying the case as a cold case exercise at the Police Academy. Olivia becomes almost obsessed with the murder when she discovers that her father previously worked with the investigation. She quickly realizes that she must get a hold of the principal investigator, detective Tom Stilton, but he seems to have disappeared from the face of the Earth.

Detective Roland Hassel's father figure and mentor, Yngve Ruda, is brutally murdered in the middle of the street. Devastated, Hassel decides to undertake his own covert investigation to find Ruda's killer and avenge him with the support of 'Triton', a special task force consisting of Hassel's most devoted co-workers. But Hassel's obsession with the case affects his family as well. As Hassel, his girlfriend Daniela and his 14-year-old stepdaughter Vida struggle to stay together as a real family they find themselves in a downward spiral taking them further and further into an abyss. Meanwhile, the evidence on Ruda's killer leads away from the street and up the corridors of power in Stockholm and Brussels. But Hassel's battle against crime and corruption knows no boundaries and he will stop at nothing.

Detective Roland Hassel's father figure and mentor, Yngve Ruda, is brutally murdered in the middle of the street. Devastated, Hassel decides to undertake his own covert investigation to find Ruda's killer and avenge him with the support of 'Triton', a special task force consisting of Hassel's most devoted co-workers. But Hassel's obsession with the case affects his family as well. As Hassel, his girlfriend Daniela and his 14-year-old stepdaughter Vida struggle to stay together as a real family they find themselves in a downward spiral taking them further and further into an abyss. Meanwhile, the evidence on Ruda's killer leads away from the street and up the corridors of power in Stockholm and Brussels. But Hassel's battle against crime and corruption knows no boundaries and he will stop at nothing.

Detective Roland Hassel's father figure and mentor, Yngve Ruda, is brutally murdered in the middle of the street. Devastated, Hassel decides to undertake his own covert investigation to find Ruda's killer and avenge him with the support of 'Triton', a special task force consisting of Hassel's most devoted co-workers. But Hassel's obsession with the case affects his family as well. As Hassel, his girlfriend Daniela and his 14-year-old stepdaughter Vida struggle to stay together as a real family they find themselves in a downward spiral taking them further and further into an abyss. Meanwhile, the evidence on Ruda's killer leads away from the street and up the corridors of power in Stockholm and Brussels. But Hassel's battle against crime and corruption knows no boundaries and he will stop at nothing.