Two years after former detective Sarah Lund was divested of her investigative role and transferred to a low-key job in the country, the body of a female lawyer is found murdered in macabre and puzzling circumstances and Lund’s former boss at Copenhagen police HQ finds that he has no choice but to call her back in to assist with the investigation. Initially reluctant, Lund soon becomes engrossed with the case. As police grapple with what few clues they possess, newly-appointed Minister for Justice, Thomas Buch, strives to oversee some intricate political negotiations between parliamentary parties over the introduction of a series of new anti-terrorism laws. At the same time, soldier Jens Peter Raben awaits release from the psychiatric ward he was committed to following a nervous breakdown.
The police now have two murder cases, both victims having military backgrounds. Sarah Lund and Ulrik Strange start to investigate the possibility of a link between the two. In parliament, while in the middle of complicated political negotiations, Buch deals with the publicised terror threat and a possible connection to Islamist fundamentalists. Meanwhile at Herstedvester Prison, Jens Peter Raben is still in isolation when he finds out that his friend has been murdered.
Having escaped from Herstedvester Prison, Jens Peter Raben sets out to track down a member of his former army squad. When an Islamist activist is arrested as the main murder suspect, Lund and her partner Strange disagree on the direction of the investigation. In parliament, young justice minister Thomas Buch must fend off accusations of a cover-up regarding a previously unpublished Special Branch memo.
After yet another gruesome murder is discovered, all clues indicate that the perpetrator of the first two killings may be responsible. But Special Branch is no longer convinced that police have the right suspect. Justice minister Thomas Buch, still under pressure, discovers some key secrets about his predecessor.
Lund and Strange travel to Sweden to question and protect the only other surviving member of Raben’s former army squad. But Raben himself is on the same mission. Having lost face with the prime minister, Buch is pressured into passing the much-negotiated anti-terrorism bill. Will he agree to the new draconian measures against his own better judgement? Top police brass and Special Branch interfere with the investigation, but Lund persists and has a breakthrough when she suddenly sees the case from a new angle.
Lund is convinced that the body of the fallen soldier, Per K Moller, is not the one in the buried coffin and orders it to be exhumed. Now the sole survivor of his former squad, Jens Peter Raben realises that the preacher lied about his acquaintance with Anne Dragsholm. Thomas Buch is still in the hot seat and tries to uncover the mysterious motivations of his predecessor, former justice minister Monberg.
Having been taken off the case, Lund continues to chase the perpetrator but finds herself in danger. Justice Minister Thomas Buch faces the consequences of his predecessor’s desperate actions and decides to go out on a limb in response – when a journalist steps forward to reveal a macabre, and thus unknown, fact relating to the suppressed military investigation. Raben is tracking his wife’s movements and Special Branch, in turn, is tracking Raben’s.
Raben is in critical condition after being shot, but the accusations he made prior to his shooting leave Brix and Lund in doubt over the neutrality of officers within their own ranks. Buch’s attack on the minister of defence is decisively refuted and it looks like the prime minister’s demands in light of this new debacle might finally wear down Buch’s determination. Will the young, tenacious minister admit defeat and throw in the towel? Meanwhile, the focus of the investigation shifts once again and Brix goes out on a limb to take a risky decision.
Lund and Strange are in Afghanistan on a mission to track down the killer. Pressing on with the investigation back home, Brix decides to conduct a search at the army barracks. Justice minister Thomas Buch remains hellbent on getting to the bottom of what he believes to be a top-level cover-up and goes out of his way to generate turmoil within the cabinet with his revelations. The cabinet, in turn, is less than impressed. Raben is once again preparing to face a court hearing and, despite pressure from all sides, refuses to retract his inflammatory statement.
Lund and Strange return from Afghanistan with new, incontrovertible evidence, while Brix and his team are getting their heads around what appear to be important findings in the investigation. Raben and Jarnvig must reluctantly work together when Louise is in danger. In parliament, rumour has it that the prime minister has plans for a cabinet reshuffle, while Buch develops a new suspicion that someone has been leading him astray – but who and why?